Re: [PATCH] drm/bridge: imx93-mipi-dsi: Fix mode validation

[Frank Li <Frank.li@nxp.com>]

On Fri, Feb 27, 2026 at 03:36:41PM +0800, Liu Ying wrote:
> Instead of checking the last bridge's operation bit masks against
> DRM_BRIDGE_OP_DETECT and DRM_BRIDGE_OP_EDID to determine if allowing
> +/-0.5% pixel clock rate deviation, check any bridge after this bridge,
> because the last bridge is usually a display connector bridge without
> any operation bit mask when the clock rate deviation is allowed.
>
> Fixes: ce62f8ea7e3f ("drm/bridge: imx: Add i.MX93 MIPI DSI support")
> Fixes: 5849eff7f067 ("drm/bridge: imx93-mipi-dsi: use drm_bridge_chain_get_last_bridge()")
> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c | 33 ++++++++++++++++-------------
>  1 file changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c b/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
> index 8f312f9edf97..6d65df9ed970 100644
> --- a/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
> @@ -493,21 +493,24 @@ static enum drm_mode_status
>  imx93_dsi_validate_mode(struct imx93_dsi *dsi, const struct drm_display_mode *mode)
>  {
>  	struct drm_bridge *dmd_bridge = dw_mipi_dsi_get_bridge(dsi->dmd);
> -	struct drm_bridge *last_bridge __free(drm_bridge_put) =
> -		drm_bridge_chain_get_last_bridge(dmd_bridge->encoder);
> -
> -	if ((last_bridge->ops & DRM_BRIDGE_OP_DETECT) &&
> -	    (last_bridge->ops & DRM_BRIDGE_OP_EDID)) {
> -		unsigned long pixel_clock_rate = mode->clock * 1000;
> -		unsigned long rounded_rate;
> -
> -		/* Allow +/-0.5% pixel clock rate deviation */
> -		rounded_rate = clk_round_rate(dsi->clk_pixel, pixel_clock_rate);
> -		if (rounded_rate < pixel_clock_rate * 995 / 1000 ||
> -		    rounded_rate > pixel_clock_rate * 1005 / 1000) {
> -			dev_dbg(dsi->dev, "failed to round clock for mode " DRM_MODE_FMT "\n",
> -				DRM_MODE_ARG(mode));
> -			return MODE_NOCLOCK;
> +
> +	drm_for_each_bridge_in_chain_from(dmd_bridge, bridge) {
> +		if ((bridge->ops & DRM_BRIDGE_OP_DETECT) &&
> +		    (bridge->ops & DRM_BRIDGE_OP_EDID)) {
> +			unsigned long pixel_clock_rate = mode->clock * 1000;
> +			unsigned long rounded_rate;
> +
> +			/* Allow +/-0.5% pixel clock rate deviation */
> +			rounded_rate = clk_round_rate(dsi->clk_pixel, pixel_clock_rate);
> +			if (rounded_rate < pixel_clock_rate * 995 / 1000 ||
> +			    rounded_rate > pixel_clock_rate * 1005 / 1000) {
> +				dev_dbg(dsi->dev,
> +					"failed to round clock for mode " DRM_MODE_FMT "\n",
> +					DRM_MODE_ARG(mode));
> +				return MODE_NOCLOCK;
> +			}
> +
> +			break;
>  		}
>  	}
>
>
> ---
> base-commit: 877552aa875839314afad7154b5a561889e87ea9
> change-id: 20260227-imx93-mipi-dsi-fix-mode-validation-425c872a2493
>
> Best regards,
> --
> Liu Ying <victor.liu@nxp.com>
>