Hi Sakari, On 23-09-13 15:27, Sakari Ailus wrote: > Hi Andrey, > > On Fri, Aug 18, 2023 at 08:34:16PM +0300, Andrey Skvortsov wrote: > > If system was suspended while camera sensor was used, data and > > interrupts were still coming from sensor and that caused unstable > > system. Sometimes system hanged during a resume. Use > > pm_runtime_force_* helpers in order to support system suspend. > > > > Signed-off-by: Andrey Skvortsov <andrej.skvortzov@xxxxxxxxx> > > Thanks for the patch. > > It's not been documented really how system suspend and resume should > work for complex cameras. But I don't think it can be done by drivers > separately as the CSI-2 bus initialisation requires actions from both > sender and receiver drivers, at particular points of time. Thanks for the review. I've tested this on PinePhone A64. It uses DVP, maybe because of that system suspend/resume worked good in my case. Originally I've implemented system suspend/resume similar to this [1] or [2] as I've seen this approach in other mainlined drivers. But some drivers reuse pm_runtime_force_* helpers, so I've went with this. Do you think it would be better to use something like [2] until there is better well defined way for system suspend/resume for complex cameras? > > So I think we'll need to initiate this from the driver handling DMA, just > as starting and stopping streaming. Even then, there needs to be a > certainty that the sensor device has resumed before streaming is started. I > recall Laurent suggested device links for that purpose, but I don't think > any work has been done to implement it that way. 1. https://salsa.debian.org/Mobian-team/devices/kernels/sunxi64-linux/-/blob/mobian-6.1/debian/patches/camera/0076-media-gc2145-implement-system-suspend.patch 2. https://elixir.bootlin.com/linux/latest/source/drivers/media/i2c/imx219.c#L1159 -- Best regards, Andrey Skvortsov
