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

[Stefan Wahren <wahrenst@gmx.net>]

Hi Maxime,

Am 02.07.24 um 15:48 schrieb Maxime Ripard:
> 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?
i saw that other drm drivers used drm_mode_config_helper_suspend() in
the RUNTIME_PM_OPS. But i agree, it should be better moved to
SYSTEM_SLEEP_PM_OPS.
> 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?
tbh I noticed that HDMI re-detection didn't worked in my setup 6.10-rcX
before this series. I need to investigate ...
>
> Maxime