Re: [PATCH 07/11] drm/vc4: hdmi: Disable connector status polling during suspend

[Maxime Ripard <mripard@kernel.org>]

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Hi,

On Sun, Jun 30, 2024 at 05:36:48PM GMT, Stefan Wahren wrote:
> Suspend of VC4 HDMI will likely triggers a warning from
> vc4_hdmi_connector_detect_ctx() during poll of connector status.
> The power management will prevent the resume and keep the relevant
> power domain disabled.
> 
> Since there is no reason to poll the connector status during
> suspend, the polling should be disabled during this.
> 
> It not possible to use drm_mode_config_helper_suspend() here,
> because the callbacks might be called during bind phase and not all
> components are fully initialized.
> 
> Link: https://lore.kernel.org/dri-devel/7003512d-7303-4f41-b0d6-a8af5bf8e497@gmx.net/
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
> ---
>  drivers/gpu/drm/vc4/vc4_hdmi.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index b3a42b709718..e80495cea6ac 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -3106,6 +3106,13 @@ static int vc5_hdmi_init_resources(struct drm_device *drm,
>  static int vc4_hdmi_runtime_suspend(struct device *dev)
>  {
>  	struct vc4_hdmi *vc4_hdmi = dev_get_drvdata(dev);
> +	struct drm_device *drm = vc4_hdmi->connector.dev;
> +
> +	/*
> +	 * Don't disable polling if it was never initialized
> +	 */
> +	if (drm && drm->mode_config.poll_enabled)
> +		drm_kms_helper_poll_disable(drm);

Does it make sense to add it to runtime_suspend?

What if the board boots without a display connected, and only after a
while one is connected? Wouldn't that prevent the driver from detecting
it?

Maxime

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