linux-kernel - Re: [PATCH v2 1/3] drm/bridge: parade-ps8640: Don't try to enable VDO if poweron fails

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Date:   Wed, 10 Nov 2021 14:42:32 +0200
From:   Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, a.hajda@...sung.com
Cc:     narmstrong@...libre.com, robert.foss@...aro.org,
        Laurent.pinchart@...asonboard.com, jonas@...boo.se,
        jernej.skrabec@...il.com, airlied@...ux.ie, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, kernel@...labora.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] drm/bridge: parade-ps8640: Don't try to enable VDO
 if poweron fails



On 02.11.21 11:36, AngeloGioacchino Del Regno wrote:
> If the bridge cannot get powered on, there's no reason to try to
> communicate with it: change the ps8640_bridge_poweron function to
> return an error value to the caller, so that we can avoid calling
> ps8640_bridge_vdo_control() in ps8640_pre_enable() if the poweron
> sequence fails.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

Reviewed-by: Dafna Hirschfeld <dafna.hirschfeld@...labora.com>

> ---
>   drivers/gpu/drm/bridge/parade-ps8640.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> index 4b36e4dc78f1..8c5402947b3c 100644
> --- a/drivers/gpu/drm/bridge/parade-ps8640.c
> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> @@ -293,19 +293,19 @@ static int ps8640_bridge_vdo_control(struct ps8640 *ps_bridge,
>   	return 0;
>   }
>   
> -static void ps8640_bridge_poweron(struct ps8640 *ps_bridge)
> +static int ps8640_bridge_poweron(struct ps8640 *ps_bridge)
>   {
>   	struct regmap *map = ps_bridge->regmap[PAGE2_TOP_CNTL];
>   	int ret, status;
>   
>   	if (ps_bridge->powered)
> -		return;
> +		return 0;
>   
>   	ret = regulator_bulk_enable(ARRAY_SIZE(ps_bridge->supplies),
>   				    ps_bridge->supplies);
>   	if (ret < 0) {
>   		DRM_ERROR("cannot enable regulators %d\n", ret);
> -		return;
> +		return ret;
>   	}
>   
>   	gpiod_set_value(ps_bridge->gpio_powerdown, 0);
> @@ -352,11 +352,13 @@ static void ps8640_bridge_poweron(struct ps8640 *ps_bridge)
>   
>   	ps_bridge->powered = true;
>   
> -	return;
> +	return 0;
>   
>   err_regulators_disable:
>   	regulator_bulk_disable(ARRAY_SIZE(ps_bridge->supplies),
>   			       ps_bridge->supplies);
> +
> +	return ret;
>   }
>   
>   static void ps8640_bridge_poweroff(struct ps8640 *ps_bridge)
> @@ -381,7 +383,9 @@ static void ps8640_pre_enable(struct drm_bridge *bridge)
>   	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
>   	int ret;
>   
> -	ps8640_bridge_poweron(ps_bridge);
> +	ret = ps8640_bridge_poweron(ps_bridge);
> +	if (ret)
> +		return;
>   
>   	ret = ps8640_bridge_vdo_control(ps_bridge, ENABLE);
>   	if (ret < 0)
>