drm/msm/dp: account for widebus and yuv420 during mode validation

[ Upstream commit df9cf85 ]

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.

Cc: stable@vger.kernel.org
Fixes: 757a2f3 ("drm/msm/dp: enable widebus feature for display port")
Fixes: 6db6e56 ("drm/msm/dp: change clock related programming for YUV420 over DP")
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Dale Whinham <daleyo@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/635789/
Link: https://lore.kernel.org/r/20250206-dp-widebus-fix-v2-1-cb89a0313286@quicinc.com
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Sasha Levin

drivers/gpu/drm/msm/dp/dp_display.c

@@ -928,16 +928,17 @@ enum drm_mode_status dp_bridge_mode_valid(struct drm_bridge *bridge,
 		return -EINVAL;
 	}
 
-	if (mode->clock > DP_MAX_PIXEL_CLK_KHZ)
-		return MODE_CLOCK_HIGH;
-
 	dp_display = container_of(dp, struct dp_display_private, dp_display);
 	link_info = &dp_display->panel->link_info;
 
-	if (drm_mode_is_420_only(&dp->connector->display_info, mode) &&
-	    dp_display->panel->vsc_sdp_supported)
+	if ((drm_mode_is_420_only(&dp->connector->display_info, mode) &&
+	     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;

drivers/gpu/drm/msm/dp/dp_drm.c

@@ -257,7 +257,10 @@ static enum drm_mode_status 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;
 
 	/*