4.4 ipu_param_mem.h头文件分析

1.下面这两个结构体是本文件的核心结构体。

struct ipu_ch_param_word { uint32_t data[5]; uint32_t res[3];
};

struct ipu_ch_param { struct ipu_ch_param_word word[2];
};

因为CPMEM是两个160位的word，所以每个word使用5个uint32_t类型来表示，同时有两个word。

2.这个宏暂时不分析，在后面用到的时候再分析。

#define ipu_ch_param_addr(ipu, ch) (((struct ipu_ch_param *)ipu->cpmem_base) + (ch))

3._param_word宏

#define _param_word(base, w) \ (((struct ipu_ch_param *)(base))->word[(w)].data)

这个宏有两个参数，第一个参数是一个起始地址值，它一般是一个指针，在宏中会进行强制类型转化；第二个参数是第几个word，看ipu_ch_param结构体，它的取值为0和1。

这个宏的意思是根据base这个起始地址值取到里面的第w个word的data数据段。

4.ipu_ch_param_set_field宏

#define ipu_ch_param_set_field(base, w, bit, size, v) { \ int i = (bit) / 32; \ int off = (bit) % 32; \ _param_word(base, w)[i] |= (v) << off; \ if (((bit)+(size)-1)/32 > i) { \ _param_word(base, w)[i + 1] |= (v) >> (off ? (32 - off) : 0); \ } \
}

这个宏有5个参数，前两个参数与_param_word宏中的参数相同，它们也确实是给_param_word宏使用的。第三个参数bit表示某一个数据在通过_param_word宏所找到的data数据段中的准确起始bit位，因为data数据段是uint32_tdata[5]的，所以这个值的范围为0～160。size表示数据所占的位数。v表示传入的数据字面值。

这个宏的意思是首先通过(bit)/32来计算出这个数据的起始bit在data数组成员中的哪一个（因为data数组有5个成员）。然后off表示这个数据在data数组成员中的偏移值。然后通过_param_word(base,w)[i]来找到对应的data数组成员。同时这个宏中也给出了这个数据所占的位数：size，如果bit所在的data数组成员放不下这么多size数的话，就需要在data数组中的下一个数组成员中存储剩下的bit。

注意在数据的存储过程中涉及到大端小端的问题，对大端小端的解释：http://www.cnblogs.com/wuyuegb2312/archive/2013/06/08/3126510.html#《轻松记住大端小端的含义（附对大端和小端的解释）》

以下面这个函数中的各个数据为例来解释一下：

static inline void _ipu_ch_params_set_packing(struct ipu_ch_param *p, int red_width, int red_offset, int green_width, int green_offset, int blue_width, int blue_offset, int alpha_width, int alpha_offset)
{ /* Setup red width and offset */ ipu_ch_param_set_field(p, 1, 116, 3, red_width - 1); ipu_ch_param_set_field(p, 1, 128, 5, red_offset); /* Setup green width and offset */ ipu_ch_param_set_field(p, 1, 119, 3, green_width - 1); ipu_ch_param_set_field(p, 1, 133, 5, green_offset); /* Setup blue width and offset */ ipu_ch_param_set_field(p, 1, 122, 3, blue_width - 1); ipu_ch_param_set_field(p, 1, 138, 5, blue_offset); /* Setup alpha width and offset */ ipu_ch_param_set_field(p, 1, 125, 3, alpha_width - 1); ipu_ch_param_set_field(p, 1, 143, 5, alpha_offset);
}

首先以ipu_ch_param_set_field( p, 1, 116, 3, red_width – 1)为例：

#define ipu_ch_param_set_field( base,  w,   bit,  size,        v) { \ int i = (bit) / 32; \ int off = (bit) % 32; \ _param_word(base, w)[i] |= (v) << off; \ if (((bit)+(size)-1)/32 > i) { \ _param_word(base, w)[i + 1] |= (v) >> (off ? (32 - off) : 0); \ } \
}

解释：

i= 116/32= 3；

off= 116%32 = 20；

#define _param_word(base, w) \ (((struct ipu_ch_param *)(base))->word[(w)].data)

_param_word(base,w)[i] |= (v) << off

==>p->word[w].data[i]|= (v) << off

==>p->word[1].data[3] |= (red_width – 1)<<20;

如下图所示：

然后继续往下执行：

ipu_ch_param_set_field(p, 1, 119, 3, green_width – 1);
ipu_ch_param_set_field(p, 1, 122, 3, blue_width – 1);
ipu_ch_param_set_field(p, 1, 125, 3, alpha_width - 1);

同样，它最终就会在119的位置存储（green_width– 1），在122的位置存储（blue_width– 1），在125的位置存储（alpha_width– 1）。

它们详细表示如下：

同样对于

ipu_ch_param_set_field(p, 1, 128, 5, red_offset);
ipu_ch_param_set_field(p, 1, 133, 5, green_offset);
ipu_ch_param_set_field(p, 1, 138, 5, blue_offset);
ipu_ch_param_set_field(p, 1, 143, 5, alpha_offset);

它们详细表示如下：

再分析一个ipu_ch_param_set_field函数中w=1, bit = 125, size = 13 的情况，对大端小端理解的更清楚。

i= 125/32 = 3；

off= 125%32 = 29；

_param_word(base,w)[i] |= (v) << off

==>p->word[w].data[i] |= (v) << off

==>p->word[1].data[3] |= (v)<<29;

if(((bit)+(size)-1)/32 > i) （125+12）/32= 4 > 3成立，所以会执行if下面的语句:

_param_word(base,w)[i + 1] |= (v) >> (off ? (32 - off) : 0);

==>_param_word(base,w)[4] |= (v) >> 3

==>p->word[1].data[4]|=(v) >> 3

重要的部分我用红色标出了，

从这里可以看出来，它的存储方式是将v的前10位存在了data[4]中，而v的后3位存在了data[3]中，从这里可以看出来，数据的存储方式是小端模式。

5.ipu_ch_param_set_field_io宏

#define ipu_ch_param_set_field_io(base, w, bit, size, v) { \ int i = (bit) / 32; \ int off = (bit) % 32; \ unsigned reg_offset; \ u32 temp; \ reg_offset = sizeof(struct ipu_ch_param_word) * w / 4; \ reg_offset += i; \ temp = readl((u32 *)base + reg_offset); \ temp |= (v) << off; \ writel(temp, (u32 *)base + reg_offset); \ if (((bit)+(size)-1)/32 > i) { \ reg_offset++; \ temp = readl((u32 *)base + reg_offset); \ temp |= (v) >> (off ? (32 - off) : 0); \ writel(temp, (u32 *)base + reg_offset); \ } \
}

这个宏根据base，w，bit的值计算出寄存器的位置，然后将v的值写进去。

但是这个ipu_ch_param_set_field_io宏与上面那个ipu_ch_param_set_field宏有什么不同呢？

往下搜索源码可以发现，虽然这两个宏的第一个参数都是base，但是他们两个不相同：

ipu_ch_param_set_field(¶ms, 0, 125, 13, width – 1);
ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, ch), 0, 113, 1, 1);

而这个ipu_ch_param_addr宏就是本文件开始的那个宏

#defineipu_ch_param_addr(ipu, ch) (((struct ipu_ch_param *)ipu->cpmem_base)+ (ch))

这个宏根据ipu和ch两个参数来找到对应寄存器的基址，具体来说就是根据ipu_soc结构体里面存放的cpmem_base寄存器的地址，ch是一般是uint32_t类型的dmachannel，通过这两个参数来找到对应寄存器的基地址。所以这个cpmem_base寄存器是设置dmachannel的关键寄存器。

对比上面两条语句，可以发现ipu_ch_param_set_field宏用于设置structipu_ch_param结构体参数params中某些位的值。而ipu_ch_param_set_field_io宏根据传入的ipu和ch参数来找到某个寄存器的基址，然后修改这个寄存器中的某些位。

以下的几个宏都与这两种情况类似。

6.ipu_ch_param_mod_field宏

#define ipu_ch_param_mod_field(base, w, bit, size, v) { \ int i = (bit) / 32; \ int off = (bit) % 32; \ u32 mask = (1UL << size) - 1; \ u32 temp = _param_word(base, w)[i]; \ temp &= ~(mask << off); \ _param_word(base, w)[i] = temp | (v) << off; \ if (((bit)+(size)-1)/32 > i) { \ temp = _param_word(base, w)[i + 1]; \ temp &= ~(mask >> (32 - off)); \ _param_word(base, w)[i + 1] = \ temp | ((v) >> (off ? (32 - off) : 0)); \ } \
}

这个函数首先为size大小设置掩码，比如size=7,这个mask就等于111111（二进制）,然后通过temp&= ~(mask << off)将这几位都清零，最后再通过temp| (v) << off将v的值写到这几位中。修改某些位值的时候，一定要先清零了再写。

7.ipu_ch_param_mod_field_io宏

#define ipu_ch_param_mod_field_io(base, w, bit, size, v) { \ int i = (bit) / 32; \ int off = (bit) % 32; \ u32 mask = (1UL << size) - 1; \ unsigned reg_offset; \ u32 temp; \ reg_offset = sizeof(struct ipu_ch_param_word) * w / 4; \ reg_offset += i; \ temp = readl((u32 *)base + reg_offset); \ temp &= ~(mask << off); \ temp |= (v) << off; \ writel(temp, (u32 *)base + reg_offset); \ if (((bit)+(size)-1)/32 > i) { \ reg_offset++; \ temp = readl((u32 *)base + reg_offset); \ temp &= ~(mask >> (32 - off)); \ temp |= ((v) >> (off ? (32 - off) : 0)); \ writel(temp, (u32 *)base + reg_offset); \ } \
}

这个宏与上一个宏类似，修改寄存器中某些位的值。

8.ipu_ch_param_read_field宏

#define ipu_ch_param_read_field(base, w, bit, size) ({ \ u32 temp2; \ int i = (bit) / 32; \ int off = (bit) % 32; \ u32 mask = (1UL << size) - 1; \ u32 temp1 = _param_word(base, w)[i]; \ temp1 = mask & (temp1 >> off); \ if (((bit)+(size)-1)/32 > i) { \ temp2 = _param_word(base, w)[i + 1]; \ temp2 &= mask >> (off ? (32 - off) : 0); \ temp1 |= temp2 << (off ? (32 - off) : 0); \ } \ temp1; \
})

这个宏的意思是读取某些位的值，这个宏最后的结果是temp1的值。

9.ipu_ch_param_read_field_io宏

#define ipu_ch_param_read_field_io(base, w, bit, size) ({ \ u32 temp1, temp2; \ int i = (bit) / 32; \ int off = (bit) % 32; \ u32 mask = (1UL << size) - 1; \ unsigned reg_offset; \ reg_offset = sizeof(struct ipu_ch_param_word) * w / 4; \ reg_offset += i; \ temp1 = readl((u32 *)base + reg_offset); \ temp1 = mask & (temp1 >> off); \ if (((bit)+(size)-1)/32 > i) { \ reg_offset++; \ temp2 = readl((u32 *)base + reg_offset); \ temp2 &= mask >> (off ? (32 - off) : 0); \ temp1 |= temp2 << (off ? (32 - off) : 0); \ } \ temp1; \
})

这个宏的意思是读取某个寄存器中某些位的值，最后的结果是temp1。

10.__ipu_ch_get_third_buf_cpmem_num函数

static inline int __ipu_ch_get_third_buf_cpmem_num(int ch)
{ switch (ch) { case 8: return 64; case 9: return 65; case 10: return 66; case 13: return 67; case 21: return 68; case 23: return 69; case 27: return 70; case 28: return 71; default: return -EINVAL; } return 0;
}

这个函数的大致意思是从函数传入的参数ch中获取到第三个buffer的起始地址。

11._ipu_ch_params_set_packing函数

static inline void _ipu_ch_params_set_packing(struct ipu_ch_param *p, int red_width, int red_offset, int green_width, int green_offset, int blue_width, int blue_offset, int alpha_width, int alpha_offset)
{ /* Setup red width and offset */ ipu_ch_param_set_field(p, 1, 116, 3, red_width - 1); ipu_ch_param_set_field(p, 1, 128, 5, red_offset); /* Setup green width and offset */ ipu_ch_param_set_field(p, 1, 119, 3, green_width - 1); ipu_ch_param_set_field(p, 1, 133, 5, green_offset); /* Setup blue width and offset */ ipu_ch_param_set_field(p, 1, 122, 3, blue_width - 1); ipu_ch_param_set_field(p, 1, 138, 5, blue_offset); /* Setup alpha width and offset */ ipu_ch_param_set_field(p, 1, 125, 3, alpha_width - 1); ipu_ch_param_set_field(p, 1, 143, 5, alpha_offset);
}

这个函数在前面分析了，它主要目的是设置第一个参数p里面的red_width，red_offset，green_width，green_offset等信息。这个函数在_ipu_ch_param_init函数中调用，比如下面这样：

_ipu_ch_params_set_packing(&params,5, 0, 6, 5, 5, 11, 8, 16);

通过这样调用，就分别设置了params中的RGB的信息，从上面可以看出来是RGB565格式的。

_ipu_ch_params_set_packing(&params,4, 4, 4, 8, 4, 12, 4, 0);

这样调用设置的是RGBA4444的格式。

12._ipu_ch_param_dump函数

这个函数是输出ipu_ch_param中的一些信息，就不分析了。

13.fill_cpmem函数

static inline void fill_cpmem(struct ipu_soc *ipu, int ch, struct ipu_ch_param *params)
{ int i, w; void *addr = ipu_ch_param_addr(ipu, ch); /* 2 words, 5 valid data */ for (w = 0; w < 2; w++) { for (i = 0; i < 5; i++) { writel(params->word[w].data[i], addr); addr += 4; } addr += 12; }
}

这个函数首先通过ipu_ch_param_addr函数根据ipu和ch参数取得dmachannel的基址，然后将params参数里面两个word里面的data数据填充到获得的这个基址中。这个函数被_ipu_ch_param_init函数中调用。

14._ipu_ch_param_init函数

static inline void _ipu_ch_param_init(struct ipu_soc *ipu, int ch, uint32_t pixel_fmt, uint32_t width, uint32_t height, uint32_t stride, uint32_t u, uint32_t v, uint32_t uv_stride, dma_addr_t addr0, dma_addr_t addr1, dma_addr_t addr2)
{ uint32_t u_offset = 0; uint32_t v_offset = 0; uint32_t bs = 0; int32_t sub_ch = 0; struct ipu_ch_param params; memset(&params<style type="text/css">p { margin-bottom: 0.25cm; line-height: 120%; }a:link {  }&params</style>, 0, sizeof(params)); ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>&params<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 0, 125, 13, width - 1);

/*将params参数里面的word[0]里面的125位到138位设置为(width- 1) */

 if (((ch == 8) || (ch == 9) || (ch == 10)) && !ipu->vdoa_en) { ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>&params<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 0, 138, 12, (height / 2) - 1); ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>&para<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>ms, 1, 102, 14, (stride * 2) – 1);

/*将params参数里面的word[0]里面的138位到150位设置为((height/ 2) - 1) */

/*将params参数里面的word[1]里面的102位到116位设置为((stride* 2) - 1) */

 } else { /* note: for vdoa+vdi- ch8/9/10, always use band mode */ ipu_ch_param_set_field(<span style="background: transparent"></span>&para<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>ms, 0, 138, 12, height - 1);
<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>      ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>&para<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>ms<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 1, 102, 14, stride - 1); }

/*将params参数里面的word[0]里面的138位到150位设置为(height- 1) */

/*将params参数里面的word[1]里面的102位到116位设置为(stride- 1) */

如果channel是8/9/10的话，从注释上来看是vdoa+vdichannel，用的是bandmode，会将params那几位设置成height/2和stride*2。

 /* EBA is 8-byte aligned */ ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>&para<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>ms<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 1, 0, 29, addr0 >> 3); ipu_ch_param_set_field(<span style="font-family:Courier 10 Pitch;">&params</span>, 1, 29, 29, addr1 >> 3); if (addr0%8) dev_warn(ipu->dev, "IDMAC%d's EBA0 is not 8-byte aligned\n", ch); if (addr1%8) dev_warn(ipu->dev, "IDMAC%d's EBA1 is not 8-byte aligned\n", ch);

/*将params参数里面的word[1]里面的0位到29位设置为(addr0>> 3)，29位到58位设置成addr1>> 3。原因是EBA是8字节对齐的，后面需要分析这里。*/

 switch (pixel_fmt) { case IPU_PIX_FMT_GENERIC: /*Represents 8-bit Generic data */ ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="font-family:Courier 10 Pitch;">&params</span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 0, 107, 3, 5);  /* bits/pixel */ ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="font-family:Courier 10 Pitch;">&params</span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 1, 85, 4, 6);    /* pix format */ ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="font-family:Courier 10 Pitch;">&params</span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 1, 78, 7, 63);   /* burst size */ break; case IPU_PIX_FMT_GENERIC_16: /* Represents 16-bit generic data */ ipu_ch_param_set_field(<style type="text/css">p { margin-bottom: 0.25cm; line-height: 120%; }a:link {  }&params</style><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="font-family:Courier 10 Pitch;">&params</span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 0, 107, 3, 3);   /* bits/pixel */ ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="font-family:Courier 10 Pitch;">&params</span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 1, 85, 4, 6);    /* pix format */ ipu_ch_param_set_field(<span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span><span style="font-family:Courier 10 Pitch;">&params</span><span style="background: transparent"><span style="font-family:Courier 10 Pitch;"><span style="font-size:12px;"><span style="background: transparent"></span></span></span></span>, 1, 78, 7, 31);   /* burst size */ break; case IPU_PIX_FMT_GENERIC_32: /*Represents 32-bit Generic data */ break; case IPU_PIX_FMT_RGB565: ipu_ch_param_set_field(¶ms, 0, 107, 3, 3); /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ _ipu_ch_params_set_packing(¶ms, 5, 0, 6, 5, 5, 11, 8, 16); break; case IPU_PIX_FMT_BGRA4444: ipu_ch_param_set_field(¶ms, 0, 107, 3, 3);    /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ _ipu_ch_params_set_packing(¶ms, 4, 4, 4, 8, 4, 12, 4, 0); break; case IPU_PIX_FMT_BGRA5551: ipu_ch_param_set_field(¶ms, 0, 107, 3, 3); /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ _ipu_ch_params_set_packing(¶ms, 5, 1, 5, 6, 5, 11, 1, 0); break; case IPU_PIX_FMT_BGR24: ipu_ch_param_set_field(¶ms, 0, 107, 3, 1);    /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 19); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 0, 8, 8, 8, 16, 8, 24); break; case IPU_PIX_FMT_RGB24: case IPU_PIX_FMT_YUV444: ipu_ch_param_set_field(¶ms, 0, 107, 3, 1);  /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 19); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 16, 8, 8, 8, 0, 8, 24); break; case IPU_PIX_FMT_VYU444: ipu_ch_param_set_field(¶ms, 0, 107, 3, 1);  /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 19); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 8, 8, 0, 8, 16, 8, 24); break; case IPU_PIX_FMT_AYUV: ipu_ch_param_set_field(¶ms, 0, 107, 3, 0);    /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 15); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 8, 8, 16, 8, 24, 8, 0); break; case IPU_PIX_FMT_BGRA32: case IPU_PIX_FMT_BGR32: ipu_ch_param_set_field(¶ms, 0, 107, 3, 0);  /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 15); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 8, 8, 16, 8, 24, 8, 0); break; case IPU_PIX_FMT_RGBA32: case IPU_PIX_FMT_RGB32: ipu_ch_param_set_field(¶ms, 0, 107, 3, 0);  /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 15); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 24, 8, 16, 8, 8, 8, 0); break; case IPU_PIX_FMT_ABGR32: ipu_ch_param_set_field(¶ms, 0, 107, 3, 0);  /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 7);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 15); /* burst size */ _ipu_ch_params_set_packing(¶ms, 8, 0, 8, 8, 8, 16, 8, 24); break; case IPU_PIX_FMT_UYVY: ipu_ch_param_set_field(¶ms, 0, 107, 3, 3);    /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 0xA);    /* pix format */ if ((ch == 8) || (ch == 9) || (ch == 10)) { ipu_ch_param_set_field(¶ms, 1, 78, 7, 15);  /* burst size */ } else { ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ } break; case IPU_PIX_FMT_YUYV: ipu_ch_param_set_field(¶ms, 0, 107, 3, 3); /* bits/pixel */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 0x8);    /* pix format */ if ((ch == 8) || (ch == 9) || (ch == 10)) { if (ipu->vdoa_en) { ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); } else { ipu_ch_param_set_field(¶ms, 1, 78, 7, 15); } } else { ipu_ch_param_set_field(¶ms, 1, 78, 7, 31);  /* burst size */ } break; case IPU_PIX_FMT_YUV420P2: case IPU_PIX_FMT_YUV420P: ipu_ch_param_set_field(¶ms, 1, 85, 4, 2);    /* pix format */ if (uv_stride < stride / 2) uv_stride = stride / 2; u_offset = stride * height; v_offset = u_offset + (uv_stride * height / 2); if ((ch == 8) || (ch == 9) || (ch == 10)) { ipu_ch_param_set_field(¶ms, 1, 78, 7, 15);  /* burst size */ uv_stride = uv_stride*2; } else { if (_ipu_is_smfc_chan(ch) && ipu->smfc_idmac_12bit_3planar_bs_fixup) bs = 15; else bs = 31; ipu_ch_param_set_field(¶ms, 1, 78, 7, bs);  /* burst size */ } break; case IPU_PIX_FMT_YVU420P: ipu_ch_param_set_field(¶ms, 1, 85, 4, 2);    /* pix format */ if (uv_stride < stride / 2) uv_stride = stride / 2; v_offset = stride * height; u_offset = v_offset + (uv_stride * height / 2); if ((ch == 8) || (ch == 9) || (ch == 10)) { ipu_ch_param_set_field(¶ms, 1, 78, 7, 15);  /* burst size */ uv_stride = uv_stride*2; } else { if (_ipu_is_smfc_chan(ch) && ipu->smfc_idmac_12bit_3planar_bs_fixup) bs = 15; else bs = 31; ipu_ch_param_set_field(¶ms, 1, 78, 7, bs);  /* burst size */ } break; case IPU_PIX_FMT_YVU422P: /* BPP & pixel format */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 1);   /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ if (uv_stride < stride / 2) uv_stride = stride / 2; v_offset = (v == 0) ? stride * height : v; u_offset = (u == 0) ? v_offset + v_offset / 2 : u; break; case IPU_PIX_FMT_YUV422P: /* BPP & pixel format */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 1);   /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ if (uv_stride < stride / 2) uv_stride = stride / 2; u_offset = (u == 0) ? stride * height : u; v_offset = (v == 0) ? u_offset + u_offset / 2 : v; break; case IPU_PIX_FMT_YUV444P: /* BPP & pixel format */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 0);   /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ uv_stride = stride; u_offset = (u == 0) ? stride * height : u; v_offset = (v == 0) ? u_offset * 2 : v; break; case IPU_PIX_FMT_NV16: ipu_ch_param_set_field(¶ms, 1, 85, 4, 1);  /* pix format */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ uv_stride = stride; u_offset = (u == 0) ? stride * height : u; break; case IPU_PIX_FMT_NV12: /* BPP & pixel format */ ipu_ch_param_set_field(¶ms, 1, 85, 4, 4);    /* pix format */ uv_stride = stride; u_offset = (u == 0) ? stride * height : u; if ((ch == 8) || (ch == 9) || (ch == 10)) { if (ipu->vdoa_en) { /* one field buffer, memory width 64bits */ ipu_ch_param_set_field(¶ms, 1, 78, 7, 63); } else { ipu_ch_param_set_field(¶ms, 1, 78, 7, 15); /* top/bottom field in one buffer*/ uv_stride = uv_stride*2; } } else { ipu_ch_param_set_field(¶ms, 1, 78, 7, 31); /* burst size */ } break; default: dev_err(ipu->dev, "mxc ipu: unimplemented pixel format\n"); break; } /*set burst size to 16*/

/*根据函数传入的pixel_fmt参数的至来决定设置params里面的哪些位。从这个switch语句中可以看出来params参数里面word[0]里面从107位开始的几位决定bits/pixel，word[1]里面从85位开始的几位决定pixformat，word[1]里面从78位开始的几位决定burstsize。*/

 if (uv_stride) ipu_ch_param_set_field(¶ms, 1, 128, 14, uv_stride - 1);

/*如果uv_stride存在的话，就设置params参数里面的word[1]的128位到142位的值为(uv_stride- 1) */

 /* Get the uv offset from user when need cropping */ if (u || v) { u_offset = u; v_offset = v; } /* UBO and VBO are 22-bit and 8-byte aligned */ if (u_offset/8 > 0x3fffff) dev_warn(ipu->dev, "IDMAC%d's U offset exceeds IPU limitation\n", ch); if (v_offset/8 > 0x3fffff) dev_warn(ipu->dev, "IDMAC%d's V offset exceeds IPU limitation\n", ch); if (u_offset%8) dev_warn(ipu->dev, "IDMAC%d's U offset is not 8-byte aligned\n", ch); if (v_offset%8) dev_warn(ipu->dev, "IDMAC%d's V offset is not 8-byte aligned\n", ch); ipu_ch_param_set_field(¶ms, 0, 46, 22, u_offset / 8); ipu_ch_param_set_field(¶ms, 0, 68, 22, v_offset / 8);

/*上面这一段代码是设置u_offset和v_offset的值。他俩分别位于params->word[0]里面的46～68和68～90位。*/

 dev_dbg(ipu->dev, "initializing idma ch %d @ %p\n", ch, ipu_ch_param_addr(ipu, ch)); fill_cpmem(ipu, ch, ¶ms);

/*辛辛苦苦设置好了params的值，肯定需要将它使用起来，就是通过这个函数来将params填充到根据ipu和ch参数找到的基址中。*/

 if (addr2) { //在ipu_common.c中调用的_ipu_ch_param_init函数中有addr2这个值。sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return;

/*通过__ipu_ch_get_third_buf_cpmem_num函数来找到第三个buffer的基址。*/

     ipu_ch_param_set_field(¶ms, 1, 0, 29, addr2 >> 3); ipu_ch_param_set_field(¶ms, 1, 29, 29, 0); if (addr2%8) dev_warn(ipu->dev, "IDMAC%d's sub-CPMEM entry%d EBA0 is not " "8-byte aligned\n", ch, sub_ch); dev_dbg(ipu->dev, "initializing idma ch %d @ %p sub cpmem\n", ch, ipu_ch_param_addr(ipu, sub_ch)); fill_cpmem(ipu, sub_ch, ¶ms); }
};

最后这些设置是在某些情况下，比如之前分析过，可能会将几个channel一起启用。这个函数被ipu_common.c中的ipu_init_channel_buffer函数所调用。

15._ipu_ch_param_set_burst_size函数

static inline void _ipu_ch_param_set_burst_size(struct ipu_soc *ipu, uint32_t ch, uint16_t burst_pixels)
{ int32_t sub_ch = 0; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 78, 7, burst_pixels - 1); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 78, 7, burst_pixels - 1);
};

这个函数用来设置或修改burst_size的值。因为在_ipu_ch_param_init初始化函数中，已经根据pixel_fmt的值设置了burst_size的初始值，在这里可以继续通过ipu和ch的值来修改他们的burst_size。这个函数被ipu_common.c中的ipu_init_channel_buffer函数所调用。

16._ipu_ch_param_get_burst_size函数

static inline int _ipu_ch_param_get_burst_size(struct ipu_soc *ipu, uint32_t ch)
{ return ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 1, 78, 7) + 1;
};

通过ipu和ch参数找到对应的寄存器然后读取它的值。这个函数被ipu_common.c中的ipu_init_channel_buffer函数所调用。

17._ipu_ch_param_get_bpp函数

static inline int _ipu_ch_param_get_bpp(struct ipu_soc *ipu, uint32_t ch)
{ return ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 0, 107, 3);
};

通过ipu和ch参数找到对应的寄存器然后读取它的值。

18._ipu_ch_param_set_buffer函数

static inline void _ipu_ch_param_set_buffer(struct ipu_soc *ipu, uint32_t ch, int bufNum, dma_addr_t phyaddr)
{ if (bufNum == 2) { ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (ch <= 0) return; bufNum = 0; } ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 29 * bufNum, 29, phyaddr / 8);
};

首先根据ipu和ch来获取基址，然后根据传入的bufNum参数来决定修改基址中的哪些位。这个函数被ipu_common.c中的ipu_update_channel_buffer函数调用。根据手册上面可以看出来，关于buffer的设置是在word[1]中从0～28,59～57，而且根据后面的分析，对于双buffer模式，这个bufNum的取值是0或者1.

19._ipu_ch_param_set_rotation函数

static inline void _ipu_ch_param_set_rotation(struct ipu_soc *ipu, uint32_t ch, ipu_rotate_mode_t rot)
{ u32 temp_rot = bitrev8(rot) >> 5; int32_t sub_ch = 0; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 0, 119, 3, temp_rot); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 119, 3, temp_rot);
};

设置rotation参数，这个函数首先根据rot的值通过bitrev8函数从byte_rev_table数组中取出对应的值，然后将那个值设置到word[0]的119～121位。这个函数被ipu_common.c中的ipu_init_channel_buffer函数调用。

20._ipu_ch_param_set_block_mode函数

static inline void _ipu_ch_param_set_block_mode(struct ipu_soc *ipu, uint32_t ch)
{ int32_t sub_ch = 0; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 0, 117, 2, 1); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 117, 2, 1);
};

设置block_mode参数，这个block_mode参数应该是位于word[0]里面的117～119位。这个函数被ipu_common.c中的ipu_init_channel_buffer函数调用。

21._ipu_ch_param_set_alpha_use_separate_channel函数

static inline void _ipu_ch_param_set_alpha_use_separate_channel(struct ipu_soc *ipu, uint32_t ch, bool option)
{ int32_t sub_ch = 0; if (option) { ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 89, 1, 1); } else { ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 89, 1, 0); }

/*根据option这个bool类型的值来设置ch对应的基址中word[1]的89位。*/

 sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; if (option) { ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 89, 1, 1); } else { ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 89, 1, 0); }
};

如果有第三个buffer的话，就设置sub_ch对应的基址中word[1]的89位。这个函数被ipu_common.c中的ipu_init_channel_buffer函数调用。

22._ipu_ch_param_set_alpha_condition_read函数

static inline void _ipu_ch_param_set_alpha_condition_read(struct ipu_soc *ipu, uint32_t ch)
{ int32_t sub_ch = 0; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 149, 1, 1); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 149, 1, 1);
};

这个函数的名字里面有read，但是里面调用的是ipu_ch_param_mod_field_io函数，他用来将ch对应的基址里面的word[1]的149位修改为1。如果有sub_ch的话，就同时修改sub_ch所对应的基址。这个函数被ipu_common.c中的ipu_init_channel_buffer函数调用。

23._ipu_ch_param_set_alpha_buffer_memory函数

static inline void _ipu_ch_param_set_alpha_buffer_memory(struct ipu_soc *ipu, uint32_t ch)
{ int alp_mem_idx; int32_t sub_ch = 0; switch (ch) { case 14: /* PRP graphic */ alp_mem_idx = 0; break; case 15: /* PP graphic */ alp_mem_idx = 1; break; case 23: /* DP BG SYNC graphic */ alp_mem_idx = 4; break; case 27: /* DP FG SYNC graphic */ alp_mem_idx = 2; break; default: dev_err(ipu->dev, "unsupported correlative channel of local " "alpha channel\n"); return; }

/*根据ch的值设置alp_mem_idx的值。*/

 ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 90, 3, alp_mem_idx); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 90, 3, alp_mem_idx);
};

这个函数首先根据ch的值来确定alp_mem_idx。然后调用ipu_ch_param_mod_field_io将ch对应基址里面的word[1]里面的90～93位修改成alp_mem_idx的值。这个函数被ipu_common.c中的ipu_init_channel_buffer函数调用。

24._ipu_ch_param_set_interlaced_scan函数

static inline void _ipu_ch_param_set_interlaced_scan(struct ipu_soc *ipu, uint32_t ch)
{ u32 stride; int32_t sub_ch = 0; sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, ch), 0, 113, 1, 1); if (sub_ch > 0) ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 113, 1, 1); stride = ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 1, 102, 14) + 1; /* ILO is 20-bit and 8-byte aligned */ if (stride/8 > 0xfffff) dev_warn(ipu->dev, "IDMAC%d's ILO exceeds IPU limitation\n", ch); if (stride%8) dev_warn(ipu->dev, "IDMAC%d's ILO is not 8-byte aligned\n", ch); ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 58, 20, stride / 8); if (sub_ch > 0) ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 58, 20, stride / 8); stride *= 2; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 102, 14, stride - 1); if (sub_ch > 0) ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 102, 14, stride - 1);
};

首先通过ipu_ch_param_set_field_io函数将ch对应基址里面word[0]的113位设为1。如果存在sub_ch的话，将sub_ch对应的基址里面word[0]的113位设为1。之后通过ipu_ch_param_read_field_io函数读取ch对应基址里面word[1]的102～116位的值来求出stride的值。之后通过ipu_ch_param_mod_field_io函数将ch对应基址里面的word[1]的58～78位设置为(stride/ 8)，将ch对应基址里面的word[1]的102～116位设置为(stride-1)，如果存在sub_ch的话需要做同样的操作。这个函数被ipu_common.c中的ipu_init_channel_buffer函数调用。

25._ipu_ch_param_set_axi_id函数

static inline void _ipu_ch_param_set_axi_id(struct ipu_soc *ipu, uint32_t ch, uint32_t id)
{ int32_t sub_ch = 0; id %= 4; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 1, 93, 2, id); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 93, 2, id);
};

根据传入的id参数来设置ch对应的基址里面word[1]的93～94位，这一位是关于axi_id的。

26._ipu_ch_param_get_axi_id函数

static inline int _ipu_ch_param_get_axi_id(struct ipu_soc *ipu, uint32_t ch)
{ return ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 1, 93, 2);
}

这个函数就是读取ch对应的基址里面word[1]的93～94位。这个函数被ipu_common.c中的ipu_ch_param_get_axi_id函数调用。

27.__ipu_ch_offset_calc函数

static inline int __ipu_ch_offset_calc(uint32_t pixel_fmt, uint32_t width, uint32_t height, uint32_t stride, uint32_t u, uint32_t v, uint32_t uv_stride, uint32_t vertical_offset, uint32_t horizontal_offset, uint32_t *u_offset, uint32_t *v_offset)
{ uint32_t u_fix = 0; uint32_t v_fix = 0; switch (pixel_fmt) { case IPU_PIX_FMT_GENERIC: case IPU_PIX_FMT_GENERIC_16: case IPU_PIX_FMT_GENERIC_32: case IPU_PIX_FMT_RGB565: case IPU_PIX_FMT_BGR24: case IPU_PIX_FMT_RGB24: case IPU_PIX_FMT_YUV444: case IPU_PIX_FMT_BGRA32: case IPU_PIX_FMT_BGR32: case IPU_PIX_FMT_RGBA32: case IPU_PIX_FMT_RGB32: case IPU_PIX_FMT_ABGR32: case IPU_PIX_FMT_UYVY: case IPU_PIX_FMT_YUYV: case IPU_PIX_FMT_GPU32_SB_ST: case IPU_PIX_FMT_GPU32_SB_SRT: case IPU_PIX_FMT_GPU32_ST: case IPU_PIX_FMT_GPU32_SRT: case IPU_PIX_FMT_GPU16_SB_ST: case IPU_PIX_FMT_GPU16_SB_SRT: case IPU_PIX_FMT_GPU16_ST: case IPU_PIX_FMT_GPU16_SRT: *u_offset = 0; *v_offset = 0; break; case IPU_PIX_FMT_YUV420P2: case IPU_PIX_FMT_YUV420P: if (uv_stride < stride / 2) uv_stride = stride / 2; *u_offset = stride * (height - vertical_offset - 1) + (stride - horizontal_offset) + (uv_stride * vertical_offset / 2) + horizontal_offset / 2; *v_offset = *u_offset + (uv_stride * height / 2); u_fix = u ? (u + (uv_stride * vertical_offset / 2) + (horizontal_offset / 2) - (stride * vertical_offset) - (horizontal_offset)) : *u_offset; v_fix = v ? (v + (uv_stride * vertical_offset / 2) + (horizontal_offset / 2) - (stride * vertical_offset) - (horizontal_offset)) : *v_offset; break; case IPU_PIX_FMT_YVU420P: if (uv_stride < stride / 2) uv_stride = stride / 2; *v_offset = stride * (height - vertical_offset - 1) + (stride - horizontal_offset) + (uv_stride * vertical_offset / 2) + horizontal_offset / 2; *u_offset = *v_offset + (uv_stride * height / 2); u_fix = u ? (u + (uv_stride * vertical_offset / 2) + (horizontal_offset / 2) - (stride * vertical_offset) - (horizontal_offset)) : *u_offset; v_fix = v ? (v + (uv_stride * vertical_offset / 2) + (horizontal_offset / 2) - (stride * vertical_offset) - (horizontal_offset)) : *v_offset; break; case IPU_PIX_FMT_YVU422P: if (uv_stride < stride / 2) uv_stride = stride / 2; *v_offset = stride * (height - vertical_offset - 1) + (stride - horizontal_offset) + (uv_stride * vertical_offset) + horizontal_offset / 2; *u_offset = *v_offset + uv_stride * height; u_fix = u ? (u + (uv_stride * vertical_offset) + horizontal_offset / 2 - (stride * vertical_offset) - (horizontal_offset)) : *u_offset; v_fix = v ? (v + (uv_stride * vertical_offset) + horizontal_offset / 2 - (stride * vertical_offset) - (horizontal_offset)) : *v_offset; break; case IPU_PIX_FMT_YUV422P: if (uv_stride < stride / 2) uv_stride = stride / 2; *u_offset = stride * (height - vertical_offset - 1) + (stride - horizontal_offset) + (uv_stride * vertical_offset) + horizontal_offset / 2; *v_offset = *u_offset + uv_stride * height; u_fix = u ? (u + (uv_stride * vertical_offset) + horizontal_offset / 2 - (stride * vertical_offset) - (horizontal_offset)) : *u_offset; v_fix = v ? (v + (uv_stride * vertical_offset) + horizontal_offset / 2 - (stride * vertical_offset) - (horizontal_offset)) : *v_offset; break; case IPU_PIX_FMT_YUV444P: uv_stride = stride; *u_offset = stride * (height - vertical_offset - 1) + (stride - horizontal_offset) + (uv_stride * vertical_offset) + horizontal_offset; *v_offset = *u_offset + uv_stride * height; u_fix = u ? (u + (uv_stride * vertical_offset) + horizontal_offset - (stride * vertical_offset) - (horizontal_offset)) : *u_offset; v_fix = v ? (v + (uv_stride * vertical_offset) + horizontal_offset - (stride * vertical_offset) - (horizontal_offset)) : *v_offset; break; case IPU_PIX_FMT_NV12: case IPU_PIX_FMT_NV16: case PRE_PIX_FMT_NV21: case PRE_PIX_FMT_NV61: uv_stride = stride; *u_offset = stride * (height - vertical_offset - 1) + (stride - horizontal_offset) + (uv_stride * vertical_offset / 2) + horizontal_offset; *v_offset = 0; u_fix = u ? (u + (uv_stride * vertical_offset / 2) + horizontal_offset - (stride * vertical_offset) - (horizontal_offset)) : *u_offset; break; default: return -EINVAL; } if (u_fix > *u_offset) *u_offset = u_fix; if (v_fix > *v_offset) *v_offset = v_fix; return 0;
}

这个函数一共有11个参数，它的最终目的是根据前9个参数设置最后2个参数的值。这个函数被本文件中_ipu_ch_offset_update函数和ipu_common.c文件中ipu_get_channel_offset函数调用。

这个函数就是根据数据格式来算出u_offset和v_offset的值，以后根据各种格式来仔细算算。

28._ipu_ch_offset_update函数

/* IDMAC U/V offset changing support */
/* U and V input is not affected, */
/* the update is done by new calculation according to */
/* vertical_offset and horizontal_offset */
static inline void _ipu_ch_offset_update(struct ipu_soc *ipu, int ch, uint32_t pixel_fmt, uint32_t width, uint32_t height, uint32_t stride, uint32_t u, uint32_t v, uint32_t uv_stride, uint32_t vertical_offset, uint32_t horizontal_offset)
{ uint32_t u_offset = 0; uint32_t v_offset = 0; uint32_t old_offset = 0; int32_t sub_ch = 0; int ret; ret = __ipu_ch_offset_calc(pixel_fmt, width, height, stride, u, v, uv_stride, vertical_offset, horizontal_offset, &u_offset, &v_offset); if (ret) { dev_err(ipu->dev, "mxc ipu: unimplemented pixel format\n"); return; } /* UBO and VBO are 22-bit and 8-byte aligned */ if (u_offset/8 > 0x3fffff) dev_warn(ipu->dev, "IDMAC%d's U offset exceeds IPU limitation\n", ch); if (v_offset/8 > 0x3fffff) dev_warn(ipu->dev, "IDMAC%d's V offset exceeds IPU limitation\n", ch); if (u_offset%8) dev_warn(ipu->dev, "IDMAC%d's U offset is not 8-byte aligned\n", ch); if (v_offset%8) dev_warn(ipu->dev, "IDMAC%d's V offset is not 8-byte aligned\n", ch); old_offset = ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 0, 46, 22); if (old_offset != u_offset / 8) ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 0, 46, 22, u_offset / 8); old_offset = ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 0, 68, 22); if (old_offset != v_offset / 8) ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, ch), 0, 68, 22, v_offset / 8); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; old_offset = ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 46, 22); if (old_offset != u_offset / 8) ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 46, 22, u_offset / 8); old_offset = ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 68, 22); if (old_offset != v_offset / 8) ipu_ch_param_mod_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 68, 22, v_offset / 8);
};

从这个函数的名字可以看出来，ipuchannel offset update：ipuchannel偏移更新，这个函数首先通过上一个__ipu_ch_offset_calc函数来计算出&u_offset和&v_offset，然后根据传入的ipu和ch参数来读取ch对应基址word[0]的46～68位中的老&u_offset偏移值和ch对应基址word[0]的68～90位中的老&v_offset偏移值，然后修改它们。重点还是u_offset和v_offset这两个值。

29._ipu_ch_params_set_alpha_width函数

static inline void _ipu_ch_params_set_alpha_width(struct ipu_soc *ipu, uint32_t ch, int alpha_width)
{ int32_t sub_ch = 0; ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, ch), 1, 125, 3, alpha_width - 1); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, sub_ch), 1, 125, 3, alpha_width - 1);
};

这个函数同样就是设置ch对应基址里面word[1]的125～128位，将它设置为(alpha_width– 1)，这一位应该就是关于alpha_width的。

30._ipu_ch_param_set_bandmode函数

static inline void _ipu_ch_param_set_bandmode(struct ipu_soc *ipu, uint32_t ch, uint32_t band_height)
{ int32_t sub_ch = 0; ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, ch), 0, 114, 3, band_height - 1); sub_ch = __ipu_ch_get_third_buf_cpmem_num(ch); if (sub_ch <= 0) return; ipu_ch_param_set_field_io(ipu_ch_param_addr(ipu, sub_ch), 0, 114, 3, band_height - 1); dev_dbg(ipu->dev, "BNDM 0x%x, ", ipu_ch_param_read_field_io(ipu_ch_param_addr(ipu, ch), 0, 114, 3));
}

这个函数同样就是设置ch对应基址里面word[0]的114～117位，将它设置为(band_height– 1)，这一位应该就是关于band_height的。

31._ipu_ch_param_bad_alpha_pos函数

/* * The IPUv3 IDMAC has a bug to read 32bpp pixels from a graphics plane * whose alpha component is at the most significant 8 bits. The bug only * impacts on cases in which the relevant separate alpha channel is enabled. * * Return true on bad alpha component position, otherwise, return false. */
static inline bool _ipu_ch_param_bad_alpha_pos(uint32_t pixel_fmt)
{ switch (pixel_fmt) { case IPU_PIX_FMT_BGRA32: case IPU_PIX_FMT_BGR32: case IPU_PIX_FMT_RGBA32: case IPU_PIX_FMT_RGB32: return true; } return false;
}

这个注释里面写的很清楚了，当IPUv3IDMAC 在从一个alpha组件位于最重要8位的图像位面读取32bpp像素的时候有一个bug，所以当pixel_fmt为32位的时候，就返回true，否则返回false。

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