linux-kernel - Re: [PATCH] drm/stm: ltdc: fix deferred endpoint management

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Message-ID: <22c16fe0-9f0b-c325-4a7c-35f3aa86dd86@st.com>
Date:   Wed, 25 Apr 2018 07:12:21 +0000
From:   Yannick FERTRE <yannick.fertre@...com>
To:     Philippe CORNU <philippe.cornu@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Vincent ABRIOU <vincent.abriou@...com>,
        "David Airlie" <airlied@...ux.ie>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Alexandre TORGUE <alexandre.torgue@...com>
Subject: Re: [PATCH] drm/stm: ltdc: fix deferred endpoint management

Hi Philippe,

Reviewed-by: Yannick Fertré <yannick.fertre@...com>


On 04/17/2018 01:34 PM, Philippe Cornu wrote:
> When a driver related to one of the endpoints is deferred
> due to probe dependencies (i2c, spi...) but the other one
> is ready, ltdc probe continues and the deferred driver
> will never be probed again.
> 
> The fix consists in waiting for all deferred endpoints before
> continuing the ltdc probe.
> 
> Signed-off-by: Philippe Cornu <philippe.cornu@...com>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index e3121d9e4230..014cef8cef37 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -987,14 +987,13 @@ int ltdc_load(struct drm_device *ddev)
>   						  &bridge[i]);
>   
>   		/*
> -		 * If at least one endpoint is ready, continue probing,
> -		 * else if at least one endpoint is -EPROBE_DEFER and
> -		 * there is no previous ready endpoints, defer probing.
> +		 * If at least one endpoint is -EPROBE_DEFER, defer probing,
> +		 * else if at least one endpoint is ready, continue probing.
>   		 */
> -		if (!ret)
> +		if (ret == -EPROBE_DEFER)
> +			return ret;
> +		else if (!ret)
>   			endpoint_not_ready = 0;
> -		else if (ret == -EPROBE_DEFER && endpoint_not_ready)
> -			endpoint_not_ready = -EPROBE_DEFER;
>   	}
>   
>   	if (endpoint_not_ready)
>