linux-kernel - Re: [PATCH 1/7] drm/bridge: analogix_dp: drop extra calls to analogix_dp_prepare

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Message-ID: <6b662c34-7a1d-4e07-aaa7-752bc0c7575f@rock-chips.com>
Date: Mon, 14 Apr 2025 09:20:00 +0800
From: Damon Ding <damon.ding@...k-chips.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Laurent.pinchart@...asonboard.com, airlied@...il.com,
 andrzej.hajda@...el.com, dri-devel@...ts.freedesktop.org,
 jernej.skrabec@...il.com, jonas@...boo.se, linux-kernel@...r.kernel.org,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
 neil.armstrong@...aro.org, quic_jesszhan@...cinc.com, rfoss@...nel.org,
 simona@...ll.ch, tzimmermann@...e.de
Subject: Re: [PATCH 1/7] drm/bridge: analogix_dp: drop extra calls to
 analogix_dp_prepare_panel()

Hi Dmitry,

On 2025/4/1 13:11, Dmitry Baryshkov wrote:
> The analogix_dp_prepare_panel() returns immediately if there is no
> attached panel. Drop several calls to this function which are performed
> when dp->plat_data->panel is NULL.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
> ---
>   drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 22 +---------------------
>   1 file changed, 1 insertion(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 042154e2d8ccd74ac2dc27fe527e810a50e08a09..ab1cfc340aa95bbf13fe021bd33227b565a5458d 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -1005,17 +1005,11 @@ static int analogix_dp_get_modes(struct drm_connector *connector)
>   {
>   	struct analogix_dp_device *dp = to_dp(connector);
>   	const struct drm_edid *drm_edid;
> -	int ret, num_modes = 0;
> +	int num_modes = 0;
>   
>   	if (dp->plat_data->panel) {
>   		num_modes += drm_panel_get_modes(dp->plat_data->panel, connector);
>   	} else {
> -		ret = analogix_dp_prepare_panel(dp, true, false);
> -		if (ret) {
> -			DRM_ERROR("Failed to prepare panel (%d)\n", ret);
> -			return 0;
> -		}
> -
>   		drm_edid = drm_edid_read_ddc(connector, &dp->aux.ddc);
>   
>   		drm_edid_connector_update(&dp->connector, drm_edid);
> @@ -1024,10 +1018,6 @@ static int analogix_dp_get_modes(struct drm_connector *connector)
>   			num_modes += drm_edid_connector_add_modes(&dp->connector);
>   			drm_edid_free(drm_edid);
>   		}
> -
> -		ret = analogix_dp_prepare_panel(dp, false, false);
> -		if (ret)
> -			DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
>   	}
>   
>   	if (dp->plat_data->get_modes)
> @@ -1087,19 +1077,9 @@ analogix_dp_detect(struct drm_connector *connector, bool force)
>   	if (dp->plat_data->panel)
>   		return connector_status_connected;
>   
> -	ret = analogix_dp_prepare_panel(dp, true, false);
> -	if (ret) {
> -		DRM_ERROR("Failed to prepare panel (%d)\n", ret);
> -		return connector_status_disconnected;
> -	}
> -
>   	if (!analogix_dp_detect_hpd(dp))
>   		status = connector_status_connected;
>   
> -	ret = analogix_dp_prepare_panel(dp, false, false);
> -	if (ret)
> -		DRM_ERROR("Failed to unprepare panel (%d)\n", ret);
> -
>   	return status;
>   }
>   
> 

With the patch series:
https://patchwork.kernel.org/project/linux-rockchip/list/?series=942183

When I verify this patch, there will be a small warning:
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c:1075:6: warning: 
unused variable 'ret' [-Wunused-variable]
         int ret;
             ^

It should be better to remove the unused 'ret'.

Best regards,
Damon