Re: [PATCH] drm/stm: ltdc: Silence -EPROBE_DEFER till bridge attached

[Philippe CORNU <philippe.cornu@foss.st.com>]

Hi Jagan,

On 7/4/21 3:59 PM, Jagan Teki wrote:
> As dw-mipi-dsi supported all possible ways to find the DSI
> devices. It can take multiple iterations for ltdc to find
> all components attached to the DSI bridge.
> 
> The current ltdc driver failed to find the endpoint as
> it returned -EINVAL for the first iteration itself. This leads
> to following error:
> 
> [    3.099289] [drm:ltdc_load] *ERROR* init encoder endpoint 0
> 
> So, check the return value and cleanup the encoder only if it's
> not -EPROBE_DEFER. This make all components in the attached DSI
> bridge found properly.
> 
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 08b71248044d..95e983d3ffb5 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -1122,8 +1122,9 @@ static int ltdc_encoder_init(struct drm_device *ddev, struct drm_bridge *bridge)
>   
>   	ret = drm_bridge_attach(encoder, bridge, NULL, 0);
>   	if (ret) {
> -		drm_encoder_cleanup(encoder);
> -		return -EINVAL;
> +		if (ret != -EPROBE_DEFER)
> +			drm_encoder_cleanup(encoder);

Many thanks for your patch.

This means that we are counting on the future success of the deferred 
probe because we do not clean the encoder...
However, Yannick gave his "Tested-by" and this patch seems useful so

Acked-by: Philippe Cornu <philippe.cornu@foss.st.com>

I will merge it friday or early next week,

Thank you
Philippe :-)


> +		return ret;
>   	}
>   
>   	DRM_DEBUG_DRIVER("Bridge encoder:%d created\n", encoder->base.id);
> @@ -1266,7 +1267,8 @@ int ltdc_load(struct drm_device *ddev)
>   		if (bridge) {
>   			ret = ltdc_encoder_init(ddev, bridge);
>   			if (ret) {
> -				DRM_ERROR("init encoder endpoint %d\n", i);
> +				if (ret != -EPROBE_DEFER)
> +					DRM_ERROR("init encoder endpoint %d\n", i);
>   				goto err;
>   			}
>   		}
> 

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