linux-kernel - Re: [PATCH v2 3/3] drm/bridge: parade-ps8640: Perform full poweroff if poweron fails

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Date:   Wed, 10 Nov 2021 14:48:27 +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 3/3] drm/bridge: parade-ps8640: Perform full poweroff
 if poweron fails



On 02.11.21 11:36, AngeloGioacchino Del Regno wrote:
> In function ps8640_bridge_poweron(), in case of a failure not relative
> to the regulators enablement, the code was disabling the regulators but
> the gpio changes that happened during the poweron sequence were not
> being reverted back to a clean poweroff state.
> 
> Since it is expected that, when we enter ps8640_bridge_poweron(), the
> powerdown and reset GPIOs are both in active state exactly as they were
> left in the poweroff function before, we can simply call function
> __ps8640_bridge_poweroff() in the failure case, reverting every change
> that was done during the power on sequence.
> 
> Of course it was chosen to call the poweroff function instead of adding
> code to revert the GPIO changes to the poweron one to avoid duplicating
> code, as we would be doing exactly what the poweroff function does.
> 
> 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 | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> index 41f5d511d516..ef1b51d8b676 100644
> --- a/drivers/gpu/drm/bridge/parade-ps8640.c
> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> @@ -344,7 +344,7 @@ static int ps8640_bridge_poweron(struct ps8640 *ps_bridge)
>   
>   	if (ret < 0) {
>   		DRM_ERROR("failed read PAGE2_GPIO_H: %d\n", ret);
> -		goto err_regulators_disable;
> +		goto err_poweroff;
>   	}
>   
>   	msleep(50);
> @@ -360,23 +360,22 @@ static int ps8640_bridge_poweron(struct ps8640 *ps_bridge)
>   	ret = regmap_update_bits(map, PAGE2_MCS_EN, MCS_EN, 0);
>   	if (ret < 0) {
>   		DRM_ERROR("failed write PAGE2_MCS_EN: %d\n", ret);
> -		goto err_regulators_disable;
> +		goto err_poweroff;
>   	}
>   
>   	/* Switch access edp panel's edid through i2c */
>   	ret = regmap_write(map, PAGE2_I2C_BYPASS, I2C_BYPASS_EN);
>   	if (ret < 0) {
>   		DRM_ERROR("failed write PAGE2_I2C_BYPASS: %d\n", ret);
> -		goto err_regulators_disable;
> +		goto err_poweroff;
>   	}
>   
>   	ps_bridge->powered = true;
>   
>   	return 0;
>   
> -err_regulators_disable:
> -	regulator_bulk_disable(ARRAY_SIZE(ps_bridge->supplies),
> -			       ps_bridge->supplies);
> +err_poweroff:
> +	__ps8640_bridge_poweroff(ps_bridge);
>   
>   	return ret;
>   }
>