环境

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firefly3399pro-JD4核心板 + 配套Firefly底板

Linux-SDK官方

需求

固定HDMI不论显示器的大小，输出固定的分辨率

解决办法

kernel/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c

static int dw_hdmi_connector_get_modes(struct drm_connector *connector)

{

struct dw_hdmi *hdmi = container_of(connector, struct dw_hdmi,

connector);

struct edid *edid;

struct drm_display_mode *mode;

//const u8 def_modes[6] = {4, 16, 31, 19, 17, 2};

//此处修改为自己要固定的分辨率vic。分辨率的结构体数组定义为在kernel/drivers/gpu/drm/drm_edid.c中定义的edid_cea_modes[]数组。

const u8 def_modes[1] = {1};

struct drm_display_info *info = &connector->display_info;

struct hdr_static_metadata *metedata =

&connector->display_info.hdmi.hdr_panel_metadata;

int i, ret = 0;

if (!hdmi->ddc)

return 0;

edid = drm_get_edid(connector, hdmi->ddc);

//if (edid) {

//直接将该处的edid注释，改成if(0)。执行else中的固定分辨率程序。

if(0){

dev_dbg(hdmi->dev, "got edid: width[%d] x height[%d]\n",

edid->width_cm, edid->height_cm);

hdmi->sink_is_hdmi = drm_detect_hdmi_monitor(edid);

hdmi->sink_has_audio = drm_detect_monitor_audio(edid);

drm_mode_connector_update_edid_property(connector, edid);

cec_notifier_set_phys_addr_from_edid(hdmi->cec_notifier, edid);

ret = drm_add_edid_modes(connector, edid);

/* Store the ELD */

drm_edid_to_eld(connector, edid);

drm_mode_connector_update_hdr_property(connector, metedata);

kfree(edid);

} else {

hdmi->sink_is_hdmi = true;

hdmi->sink_has_audio = true;

for (i = 0; i < sizeof(def_modes); i++) {

mode = drm_display_mode_from_vic_index(connector,

def_modes,

31, i);

if (mode) {

if (!i)

mode->type = DRM_MODE_TYPE_PREFERRED;

drm_mode_probed_add(connector, mode);

ret++;

}

}

info->edid_hdmi_dc_modes = 0;

info->hdmi.y420_dc_modes = 0;

info->color_formats = 0;

dev_info(hdmi->dev, "failed to get edid\n");

}

return ret;

}

分辨率结构体数组

/*

* Probably taken from CEA-861 spec.

* This table is converted from xorg's hw/xfree86/modes/xf86EdidModes.c.

*

* Index using the VIC.

*/

static const struct drm_display_mode edid_cea_modes[] = {

/* 0 - dummy, VICs start at 1 */

{ },

/* 1 - 640x480@60Hz */

{ DRM_MODE("640x480", DRM_MODE_TYPE_DRIVER, 25175, 640, 656,

752, 800, 0, 480, 490, 492, 525, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, },

/* 2 - 720x480@60Hz */

{ DRM_MODE("720x480", DRM_MODE_TYPE_DRIVER, 27000, 720, 736,

798, 858, 0, 480, 489, 495, 525, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, },

/* 3 - 720x480@60Hz */

{ DRM_MODE("720x480", DRM_MODE_TYPE_DRIVER, 27000, 720, 736,

798, 858, 0, 480, 489, 495, 525, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

/* 4 - 1280x720@60Hz */

{ DRM_MODE("1280x720", DRM_MODE_TYPE_DRIVER, 74250, 1280, 1390,

1430, 1650, 0, 720, 725, 730, 750, 0,

DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

/* 5 - 1920x1080i@60Hz */

{ DRM_MODE("1920x1080i", DRM_MODE_TYPE_DRIVER, 74250, 1920, 2008,

2052, 2200, 0, 1080, 1084, 1094, 1125, 0,

DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC |

DRM_MODE_FLAG_INTERLACE),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

/* 6 - 720(1440)x480i@60Hz */

{ DRM_MODE("720x480i", DRM_MODE_TYPE_DRIVER, 13500, 720, 739,

801, 858, 0, 480, 488, 494, 525, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC |

DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLCLK),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, },

/* 7 - 720(1440)x480i@60Hz */

{ DRM_MODE("720x480i", DRM_MODE_TYPE_DRIVER, 13500, 720, 739,

801, 858, 0, 480, 488, 494, 525, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC |

DRM_MODE_FLAG_INTERLACE | DRM_MODE_FLAG_DBLCLK),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

/* 8 - 720(1440)x240@60Hz */

{ DRM_MODE("720x240", DRM_MODE_TYPE_DRIVER, 13500, 720, 739,

801, 858, 0, 240, 244, 247, 262, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC |

DRM_MODE_FLAG_DBLCLK),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, },

/* 9 - 720(1440)x240@60Hz */

{ DRM_MODE("720x240", DRM_MODE_TYPE_DRIVER, 13500, 720, 739,

801, 858, 0, 240, 244, 247, 262, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC |

DRM_MODE_FLAG_DBLCLK),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9, },

/* 10 - 2880x480i@60Hz */

{ DRM_MODE("2880x480i", DRM_MODE_TYPE_DRIVER, 54000, 2880, 2956,

3204, 3432, 0, 480, 488, 494, 525, 0,

DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC |

DRM_MODE_FLAG_INTERLACE),

.vrefresh = 60, .picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3, },

};

结构体数组中定义了很多分辨率，就不一一列举了。