Re: [PATCH v3 09/10] media: v4l2-subdev: notify the bridge when the source power changes

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] media: missing V4L2_DEVICE_NOTIFY_RX_POWER_PRESENT producers breaks hotplug
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commit 6a92b4c6dc1e86451bb217218d03ed0f4be33caf
Author: Sascha Hauer <s.hauer@pengutronix.de>

media: v4l2-subdev: notify the bridge when the source power changes

This commit adds a new V4L2_DEVICE_NOTIFY_RX_POWER_PRESENT notification
macro. It allows subdevices to notify the bridge when the source power
changes on the connector's +5V line, so devices can act on hardware
changes instead of only handing the value to userspace.

> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
[ ... ]
> @@ -29,6 +29,14 @@
>  
>  #define	V4L2_DEVICE_NOTIFY_EVENT		_IOW('v', 2, struct v4l2_event)
>  
> +/*
> + * The source power state a receiver publishes as
> + * V4L2_CID_DV_RX_POWER_PRESENT has changed. The argument points at an
> + * unsigned int holding the same per-input mask as that control, so zero
> + * means no input sees a source.
> + */
> +#define	V4L2_DEVICE_NOTIFY_RX_POWER_PRESENT	_IOW('v', 3, unsigned int)

[Severity: Medium]
Is this notification actually emitted by any subdevices in this series?

While this macro is added to allow subdevices to notify the bridge of power
changes (and is consumed by hdmirx_notify in patch 10 to detect hotplug
events on boards lacking a dedicated 5V GPIO), it doesn't appear to be
used by any upstream subdevice drivers like adv7604 or tc358743 in this
patch series.

When a user plugs or unplugs the HDMI cable at runtime, the upstream
subdevice updates the V4L2_CID_DV_RX_POWER_PRESENT control but fails to
emit this V4L2_DEVICE_NOTIFY_RX_POWER_PRESENT event. Without the producer
side implemented, the receiver (e.g. snps_hdmirx) never receives the
notification and fails to rescan the link state.

Does this leave runtime hotplug functionality incomplete or broken on
boards that rely on this notification rather than a dedicated 5V GPIO?

> +
>  struct v4l2_device;
>  struct v4l2_ctrl_handler;
>  struct v4l2_event;

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Sashiko AI review · https://sashiko.dev/#/patchset/20261005-hdmirx-media-v3-0-71a11a2e3e76@pengutronix.de?part=9