Re: [PATCH 06/11] drm/vc4: hdmi: Handle error case of pm_runtime_resume_and_get

["Maíra Canal" <mcanal@igalia.com>]

On 6/30/24 12:36, Stefan Wahren wrote:
> The commit 0f5251339eda ("drm/vc4: hdmi: Make sure the controller is
> powered in detect") introduced the necessary power management handling
> to avoid register access while controller is powered down.
> Unfortunately it just print a warning if pm_runtime_resume_and_get()
> fails and proceed anyway.
> 
> This could happen during suspend to idle. So we must assume it is unsafe
> to access the HDMI register. So bail out properly.
> 
> Fixes: 0f5251339eda ("drm/vc4: hdmi: Make sure the controller is powered in detect")
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>

 From the docs, I see that `DRM_ERROR` was deprecated in favor of
`pr_err()` (although I'm seeing some drivers using `dev_err()`). So,
after this change, this is:

Reviewed-by: Maíra Canal <mcanal@igalia.com>

It would be nice to have a follow-up patch changing other vc4 files,
as they are using `DRM_ERROR` when returning the error from
`pm_runtime_resume_and_get()`.

Best Regards,
- Maíra

> ---
>   drivers/gpu/drm/vc4/vc4_hdmi.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index d57c4a5948c8..b3a42b709718 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -429,6 +429,7 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
>   {
>   	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
>   	enum drm_connector_status status = connector_status_disconnected;
> +	int ret;
> 
>   	/*
>   	 * NOTE: This function should really take vc4_hdmi->mutex, but
> @@ -441,7 +442,11 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
>   	 * the lock for now.
>   	 */
> 
> -	WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
> +	ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);
> +	if (ret) {
> +		DRM_ERROR("Failed to retain HDMI power domain: %d\n", ret);
> +		return status;
> +	}
> 
>   	if (vc4_hdmi->hpd_gpio) {
>   		if (gpiod_get_value_cansleep(vc4_hdmi->hpd_gpio))
> --
> 2.34.1
>