linux-kernel - Re: [PATCH] drm/panel: atna33xc20: Fix unbalanced regulator in the case HPD doesn't assert

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Date: Thu, 14 Mar 2024 15:32:09 -0700
From: Jessica Zhang <quic_jesszhan@...cinc.com>
To: <dianders@...omium.org>, Neil Armstrong <neil.armstrong@...aro.org>,
        Sam
 Ravnborg <sam@...nborg.org>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>
CC: <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/panel: atna33xc20: Fix unbalanced regulator in the
 case HPD doesn't assert



On 3/13/2024 2:12 PM, Douglas Anderson via B4 Relay wrote:
> From: Douglas Anderson <dianders@...omium.org>
> 
> When the atna33xc20 driver was first written the resume code never
> returned an error. If there was a problem waiting for HPD it just
> printed a warning and moved on. This changed in response to review
> feedback [1] on a future patch but I accidentally didn't account for
> rolling back the regulator enable in the error cases. Do so now.
> 
> [1] https://lore.kernel.org/all/5f3cf3a6-1cc2-63e4-f76b-4ee686764705@linaro.org/
> 
> Fixes: 3b5765df375c ("drm/panel: atna33xc20: Take advantage of wait_hpd_asserted() in struct drm_dp_aux")
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
>   drivers/gpu/drm/panel/panel-samsung-atna33xc20.c | 22 +++++++++++++---------
>   1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c b/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c
> index 76c2a8f6718c..9c336c71562b 100644
> --- a/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c
> +++ b/drivers/gpu/drm/panel/panel-samsung-atna33xc20.c
> @@ -109,19 +109,17 @@ static int atana33xc20_resume(struct device *dev)
>   		if (hpd_asserted < 0)
>   			ret = hpd_asserted;
>   
> -		if (ret)
> +		if (ret) {
>   			dev_warn(dev, "Error waiting for HPD GPIO: %d\n", ret);
> -
> -		return ret;
> -	}
> -
> -	if (p->aux->wait_hpd_asserted) {
> +			goto error;
> +		}
> +	} else if (p->aux->wait_hpd_asserted) {

Hi Doug,

Acked-by: Jessica Zhang <quic_jesszhan@...cinc.com>

Thanks,

Jessica Zhang

>   		ret = p->aux->wait_hpd_asserted(p->aux, HPD_MAX_US);
>   
> -		if (ret)
> +		if (ret) {
>   			dev_warn(dev, "Controller error waiting for HPD: %d\n", ret);
> -
> -		return ret;
> +			goto error;
> +		}
>   	}
>   
>   	/*
> @@ -133,6 +131,12 @@ static int atana33xc20_resume(struct device *dev)
>   	 * right times.
>   	 */
>   	return 0;
> +
> +error:
> +	drm_dp_dpcd_set_powered(p->aux, false);
> +	regulator_disable(p->supply);
> +
> +	return ret;
>   }
>   
>   static int atana33xc20_disable(struct drm_panel *panel)
> 
> ---
> base-commit: b33651a5c98dbd5a919219d8c129d0674ef74299
> change-id: 20240311-homestarpanel-regulator-f4b890ff4b7c
> 
> Best regards,
> -- 
> Douglas Anderson <dianders@...omium.org>
>