Re: [PATCH 2/2] media: uvcvideo: skip resume when writing hibernation image

Re: [PATCH 2/2] media: uvcvideo: skip resume when writing hibernation image

[Haowen Tu]

Hi Laurent,

On Tue, Apr 28, 2026 at 12:13:56PM +0300, Laurent Pinchart wrote:
> Will all leaf drivers need to implement something similar ? How does
> that scale ?

Thanks, that's a very valid concern.

If this pattern ends up being needed in multiple USB interface drivers,
then handling it in each leaf driver would clearly not scale well.

My initial motivation was that the UVC streaming resume path is reached
from usb_driver.resume(), which doesn't expose the hibernation PM
message. As a result, the driver has no way to distinguish PMSG_THAW
from PMSG_RESTORE locally.

That said, I agree this points to a USB-level design question rather
than just a UVC-specific one. I'll revisit the approach with that in
mind, and will include the USB maintainers and list in the next round.

Thanks,
Haowen

Re: [PATCH 2/2] media: uvcvideo: skip resume when writing hibernation image

[Haowen Tu]

Hi Laurent,

On Tue, Apr 28, 2026 at 12:13:56PM +0300, Laurent Pinchart wrote:
> Will all leaf drivers need to implement something similar ? How does
> that scale ?

Thanks, that's a very valid concern.

If this pattern ends up being needed in multiple USB interface drivers,
then handling it in each leaf driver would clearly not scale well.

My initial motivation was that the UVC streaming resume path is reached
from usb_driver.resume(), which doesn't expose the hibernation PM
message. As a result, the driver has no way to distinguish PMSG_THAW
from PMSG_RESTORE locally.

That said, I agree this points to a USB-level design question rather
than just a UVC-specific one. I'll revisit the approach with that in
mind, and will include the USB maintainers and list in the next round.

Thanks,
Haowen