linux-kernel - [PATCH] drm/msm/dp: account for widebus and yuv420 during mode validation

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Message-ID: <20250128-dp-widebus-fix-v1-1-b66d2265596b@quicinc.com>
Date: Tue, 28 Jan 2025 15:10:27 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>,
        Marijn Suijten
	<marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, "Simona
 Vetter" <simona@...ll.ch>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>,
        "Stephen
 Boyd" <swboyd@...omium.org>,
        Paloma Arellano <quic_parellan@...cinc.com>
CC: <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        "Abhinav
 Kumar" <quic_abhinavk@...cinc.com>
Subject: [PATCH] drm/msm/dp: account for widebus and yuv420 during mode
 validation

Widebus allows the DP controller to operate in 2 pixel per clock mode.
The mode validation logic validates the mode->clock against the max
DP pixel clock. However the max DP pixel clock limit assumes widebus
is already enabled. Adjust the mode validation logic to only compare
the adjusted pixel clock which accounts for widebus against the max DP
pixel clock. Also fix the mode validation logic for YUV420 modes as in
that case as well, only half the pixel clock is needed.

Fixes: 757a2f36ab09 ("drm/msm/dp: enable widebus feature for display port")
Fixes: 6db6e5606576 ("drm/msm/dp: change clock related programming for YUV420 over DP")
Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 10 +++++-----
 drivers/gpu/drm/msm/dp/dp_drm.c     |  5 ++++-
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 24dd37f1682bf5016bb0efbeb44489061deff060..a4b420a2d9eb7f084194f443e84a4013c9b4ef0f 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -930,16 +930,16 @@ enum drm_mode_status msm_dp_bridge_mode_valid(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (mode->clock > DP_MAX_PIXEL_CLK_KHZ)
-		return MODE_CLOCK_HIGH;
-
 	msm_dp_display = container_of(dp, struct msm_dp_display_private, msm_dp_display);
 	link_info = &msm_dp_display->panel->link_info;
 
-	if (drm_mode_is_420_only(&dp->connector->display_info, mode) &&
-	    msm_dp_display->panel->vsc_sdp_supported)
+	if ((drm_mode_is_420_only(&dp->connector->display_info, mode) &&
+	     msm_dp_display->panel->vsc_sdp_supported) || msm_dp_wide_bus_available(dp))
 		mode_pclk_khz /= 2;
 
+	if (mode_pclk_khz > DP_MAX_PIXEL_CLK_KHZ)
+		return MODE_CLOCK_HIGH;
+
 	mode_bpp = dp->connector->display_info.bpc * num_components;
 	if (!mode_bpp)
 		mode_bpp = default_bpp;
diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index d3e241ea6941615b8e274dd17426c2f8557f09b5..16b7913d1eefa8c2deb44df201a1977db23f4531 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -257,7 +257,10 @@ static enum drm_mode_status msm_edp_bridge_mode_valid(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (mode->clock > DP_MAX_PIXEL_CLK_KHZ)
+	if (msm_dp_wide_bus_available(dp))
+		mode_pclk_khz /= 2;
+
+	if (mode_pclk_khz > DP_MAX_PIXEL_CLK_KHZ)
 		return MODE_CLOCK_HIGH;
 
 	/*

---
base-commit: 2bd7708f11777d4fd436fcba62b57cff6a92e389
change-id: 20250127-dp-widebus-fix-fba78bbe242d

Best regards,
-- 
Abhinav Kumar <quic_abhinavk@...cinc.com>