Re: [PATCH 05/17] drm/msm/dp: add an API to indicate if sink supports VSC SDP

Paloma Arellano <quic_parellan@xxxxxxxxxxx> · Mon, 29 Jan 2024 15:20:09 -0800

On 1/26/2024 6:40 PM, Dmitry Baryshkov wrote:
On Sat, 27 Jan 2024 at 02:58, Paloma Arellano <quic_parellan@xxxxxxxxxxx> wrote:

On 1/25/2024 1:23 PM, Dmitry Baryshkov wrote:
On 25/01/2024 21:38, Paloma Arellano wrote:
YUV420 format is supported only in the VSC SDP packet and not through
MSA. Hence add an API which indicates the sink support which can be used
by the rest of the DP programming.
This API ideally should go to drm/display/drm_dp_helper.c
I'm not familiar how other vendors are checking if VSC SDP is supported.
So in moving this API, I'm going to let the other vendors make the
changes themselves.
Let me show it for you:

bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
{
         u8 dprx = 0;

         if (drm_dp_dpcd_readb(&intel_dp->aux, DP_DPRX_FEATURE_ENUMERATION_LIST,
                               &dprx) != 1)
                 return false;
         return dprx & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED;
}


Signed-off-by: Paloma Arellano <quic_parellan@xxxxxxxxxxx>
---
   drivers/gpu/drm/msm/dp/dp_display.c |  3 ++-
   drivers/gpu/drm/msm/dp/dp_panel.c   | 35 +++++++++++++++++++++++++----
   drivers/gpu/drm/msm/dp/dp_panel.h   |  1 +
   3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
b/drivers/gpu/drm/msm/dp/dp_display.c
index ddac55f45a722..f6b3b6ca242f8 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1617,7 +1617,8 @@ void dp_bridge_mode_set(struct drm_bridge
*drm_bridge,
           !!(dp_display->dp_mode.drm_mode.flags & DRM_MODE_FLAG_NHSYNC);
         dp_display->dp_mode.out_fmt_is_yuv_420 =
- drm_mode_is_420_only(&dp->connector->display_info, adjusted_mode);
+ drm_mode_is_420_only(&dp->connector->display_info, adjusted_mode) &&
+        dp_panel_vsc_sdp_supported(dp_display->panel);
         /* populate wide_bus_support to different layers */
       dp_display->ctrl->wide_bus_en =
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c
b/drivers/gpu/drm/msm/dp/dp_panel.c
index 127f6af995cd1..af7820b6d35ec 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -17,6 +17,9 @@ struct dp_panel_private {
       struct dp_link *link;
       struct dp_catalog *catalog;
       bool panel_on;
+    bool vsc_supported;
+    u8 major;
+    u8 minor;
   };
     static void dp_panel_read_psr_cap(struct dp_panel_private *panel)
@@ -43,9 +46,10 @@ static void dp_panel_read_psr_cap(struct
dp_panel_private *panel)
   static int dp_panel_read_dpcd(struct dp_panel *dp_panel)
   {
       int rc;
+    ssize_t rlen;
       struct dp_panel_private *panel;
       struct dp_link_info *link_info;
-    u8 *dpcd, major, minor;
+    u8 *dpcd, rx_feature;
         panel = container_of(dp_panel, struct dp_panel_private,
dp_panel);
       dpcd = dp_panel->dpcd;
@@ -53,10 +57,19 @@ static int dp_panel_read_dpcd(struct dp_panel
*dp_panel)
       if (rc)
           return rc;
   +    rlen = drm_dp_dpcd_read(panel->aux,
DP_DPRX_FEATURE_ENUMERATION_LIST, &rx_feature, 1);
+    if (rlen != 1) {
+        panel->vsc_supported = false;
+        pr_debug("failed to read DP_DPRX_FEATURE_ENUMERATION_LIST\n");
+    } else {
+        panel->vsc_supported = !!(rx_feature &
DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED);
+        pr_debug("vsc=%d\n", panel->vsc_supported);
+    }
+
       link_info = &dp_panel->link_info;
       link_info->revision = dpcd[DP_DPCD_REV];
-    major = (link_info->revision >> 4) & 0x0f;
-    minor = link_info->revision & 0x0f;
+    panel->major = (link_info->revision >> 4) & 0x0f;
+    panel->minor = link_info->revision & 0x0f;
         link_info->rate = drm_dp_max_link_rate(dpcd);
       link_info->num_lanes = drm_dp_max_lane_count(dpcd);
@@ -69,7 +82,7 @@ static int dp_panel_read_dpcd(struct dp_panel
*dp_panel)
       if (link_info->rate > dp_panel->max_dp_link_rate)
           link_info->rate = dp_panel->max_dp_link_rate;
   -    drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", major, minor);
+    drm_dbg_dp(panel->drm_dev, "version: %d.%d\n", panel->major,
panel->minor);
       drm_dbg_dp(panel->drm_dev, "link_rate=%d\n", link_info->rate);
       drm_dbg_dp(panel->drm_dev, "lane_count=%d\n",
link_info->num_lanes);
   @@ -280,6 +293,20 @@ void dp_panel_tpg_config(struct dp_panel
*dp_panel, bool enable)
       dp_catalog_panel_tpg_enable(catalog,
&panel->dp_panel.dp_mode.drm_mode);
   }
   +bool dp_panel_vsc_sdp_supported(struct dp_panel *dp_panel)
+{
+    struct dp_panel_private *panel;
+
+    if (!dp_panel) {
+        pr_err("invalid input\n");
+        return false;
+    }
+
+    panel = container_of(dp_panel, struct dp_panel_private, dp_panel);
+
+    return panel->major >= 1 && panel->minor >= 3 &&
panel->vsc_supported;
Anyway, this check is incorrect. Please compare the whole revision
against DP_DPCD_REV_13 instead of doing a maj/min comparison.
Ack

+}
+
   void dp_panel_dump_regs(struct dp_panel *dp_panel)
   {
       struct dp_catalog *catalog;
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h
b/drivers/gpu/drm/msm/dp/dp_panel.h
index 6ec68be9f2366..590eca5ce304b 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.h
+++ b/drivers/gpu/drm/msm/dp/dp_panel.h
@@ -66,6 +66,7 @@ int dp_panel_get_modes(struct dp_panel *dp_panel,
           struct drm_connector *connector);
   void dp_panel_handle_sink_request(struct dp_panel *dp_panel);
   void dp_panel_tpg_config(struct dp_panel *dp_panel, bool enable);
+bool dp_panel_vsc_sdp_supported(struct dp_panel *dp_panel);
     /**
    * is_link_rate_valid() - validates the link rate








