[PATCH v3 5/7] drm/msm/hdmi: stop using drm_bridge_connector_en/disable_hpd()

[Johan Hovold]

On Wed, Nov 02, 2022 at 09:07:03PM +0300, Dmitry Baryshkov wrote:
> The functionality of drm_bridge_connector_enable_hpd() and
> drm_bridge_connector_disable_hpd() is provided automatically by the
> drm_kms_poll helpers. Stop calling these functions manually.

I stumbled over this one when investigating a hotplug-related crash in
the MSM DRM driver which this series prevents by moving hotplug
notification enable to drm_kms_helper_poll_enable().

> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> ---
>  drivers/gpu/drm/msm/hdmi/hdmi.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/hdmi/hdmi.c b/drivers/gpu/drm/msm/hdmi/hdmi.c
> index 93fe61b86967..a540c45d4fd3 100644
> --- a/drivers/gpu/drm/msm/hdmi/hdmi.c
> +++ b/drivers/gpu/drm/msm/hdmi/hdmi.c
> @@ -348,8 +348,6 @@ int msm_hdmi_modeset_init(struct hdmi *hdmi,
>  		goto fail;
>  	}
>  
> -	drm_bridge_connector_enable_hpd(hdmi->connector);
> -
>  	ret = msm_hdmi_hpd_enable(hdmi->bridge);
>  	if (ret < 0) {
>  		DRM_DEV_ERROR(&hdmi->pdev->dev, "failed to enable HPD: %d\n", ret);

It looks like you are now enabling hotplug events before the DRM driver
is ready to receive them (i.e. msm_hdmi_hpd_enable() is called before
drm_bridge_connector_enable_hpd()).

Could this not lead to missed events or is the state being setup
correctly somewhere else?

Shouldn't the call to msm_hdmi_hpd_enable() be moved to when HPD is
enabled either way (e.g. by being converted to a hpd_enable callback)?

Johan