As per DisplayID v2.0 Errata E9 spec "DSC pass-through timing support"
VESA vendor-specific data block may contain target DSC bits per pixel
fields

Signed-off-by: Yaroslav Bolyukin <i...@lach.pw>
---
 drivers/gpu/drm/drm_edid.c  | 38 +++++++++++++++++++++++++------------
 include/drm/drm_connector.h |  6 ++++++
 include/drm/drm_displayid.h |  4 ++++
 3 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 3d0a4da661bc..aa88ac82cbe0 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -6338,7 +6338,7 @@ static void drm_parse_vesa_mso_data(struct drm_connector 
*connector,
        if (oui(vesa->oui[0], vesa->oui[1], vesa->oui[2]) != VESA_IEEE_OUI)
                return;
 
-       if (sizeof(*vesa) != sizeof(*block) + block->num_bytes) {
+       if (block->num_bytes < 5) {
                drm_dbg_kms(connector->dev,
                            "[CONNECTOR:%d:%s] Unexpected VESA vendor block 
size\n",
                            connector->base.id, connector->name);
@@ -6361,24 +6361,37 @@ static void drm_parse_vesa_mso_data(struct 
drm_connector *connector,
                break;
        }
 
-       if (!info->mso_stream_count) {
-               info->mso_pixel_overlap = 0;
-               return;
-       }
+       info->mso_pixel_overlap = 0;
+
+       if (info->mso_stream_count) {
+               info->mso_pixel_overlap = FIELD_GET(DISPLAYID_VESA_MSO_OVERLAP, 
vesa->mso);
+
+               if (info->mso_pixel_overlap > 8) {
+                       drm_dbg_kms(connector->dev,
+                                   "[CONNECTOR:%d:%s] Reserved MSO pixel 
overlap value %u\n",
+                                   connector->base.id, connector->name,
+                                   info->mso_pixel_overlap);
+                       info->mso_pixel_overlap = 8;
+               }
 
-       info->mso_pixel_overlap = FIELD_GET(DISPLAYID_VESA_MSO_OVERLAP, 
vesa->mso);
-       if (info->mso_pixel_overlap > 8) {
                drm_dbg_kms(connector->dev,
-                           "[CONNECTOR:%d:%s] Reserved MSO pixel overlap value 
%u\n",
+                           "[CONNECTOR:%d:%s] MSO stream count %u, pixel 
overlap %u\n",
                            connector->base.id, connector->name,
-                           info->mso_pixel_overlap);
-               info->mso_pixel_overlap = 8;
+                           info->mso_stream_count, info->mso_pixel_overlap);
+       }
+
+       if (block->num_bytes < 7) {
+               /* DSC bpp is optional */
+               return;
        }
 
+       info->dp_dsc_bpp = FIELD_GET(DISPLAYID_VESA_DSC_BPP_INT, 
vesa->dsc_bpp_int) * 16
+               + FIELD_GET(DISPLAYID_VESA_DSC_BPP_FRACT, vesa->dsc_bpp_fract);
+
        drm_dbg_kms(connector->dev,
-                   "[CONNECTOR:%d:%s] MSO stream count %u, pixel overlap %u\n",
+                   "[CONNECTOR:%d:%s] DSC bits per pixel %u\n",
                    connector->base.id, connector->name,
-                   info->mso_stream_count, info->mso_pixel_overlap);
+                   info->dp_dsc_bpp);
 }
 
 static void drm_update_mso(struct drm_connector *connector,
@@ -6425,6 +6438,7 @@ static void drm_reset_display_info(struct drm_connector 
*connector)
        info->mso_stream_count = 0;
        info->mso_pixel_overlap = 0;
        info->max_dsc_bpp = 0;
+       info->dp_dsc_bpp = 0;
 
        kfree(info->vics);
        info->vics = NULL;
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 7b5048516185..1d01e0146a7f 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -719,6 +719,12 @@ struct drm_display_info {
         */
        u32 max_dsc_bpp;
 
+       /**
+        * @dp_dsc_bpp: DP Display-Stream-Compression (DSC) timing's target
+        * DST bits per pixel in 6.4 fixed point format. 0 means undefined
+        */
+       u16 dp_dsc_bpp;
+
        /**
         * @vics: Array of vics_len VICs. Internal to EDID parsing.
         */
diff --git a/include/drm/drm_displayid.h b/include/drm/drm_displayid.h
index 49649eb8447e..0fc3afbd1675 100644
--- a/include/drm/drm_displayid.h
+++ b/include/drm/drm_displayid.h
@@ -131,12 +131,16 @@ struct displayid_detailed_timing_block {
 
 #define DISPLAYID_VESA_MSO_OVERLAP     GENMASK(3, 0)
 #define DISPLAYID_VESA_MSO_MODE                GENMASK(6, 5)
+#define DISPLAYID_VESA_DSC_BPP_INT     GENMASK(5, 0)
+#define DISPLAYID_VESA_DSC_BPP_FRACT   GENMASK(3, 0)
 
 struct displayid_vesa_vendor_specific_block {
        struct displayid_block base;
        u8 oui[3];
        u8 data_structure_type;
        u8 mso;
+       u8 dsc_bpp_int;
+       u8 dsc_bpp_fract;
 } __packed;
 
 /* DisplayID iteration */
-- 
2.39.1

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