(EXT) [BUG] media: imx: imx7-media-csi issue with vb2 is hanging / freezing the system

[Martin Kepplinger]

Am Freitag, dem 12.11.2021 um 15:49 +0100 schrieb Martin Kepplinger:
> 
> 
> Am 12. November 2021 13:40:43 MEZ schrieb Alexander Stein
> <alexander.stein at ew.tq-group.com>:
> > Hello Martin,
> > 
> > Am Freitag, dem 12.11.2021 um 12:23 +0100 schrieb Martin
> > Kepplinger:
> > > hi Laurent and all who it may concern,
> > > 
> > > Ever since I switches to using imx7-media-csi on imx8mq I have
> > > seen a
> > > bug that hangs /freezes the system so that I can't really save a
> > > trace
> > > or get logs for it. It happens not every time when starting
> > > streaming,
> > > but sometimes - when starting to stream frames.
> > > 
> > > It kind of looks like a lock not released or something similar,
> > > but
> > > some race condition might happen since it's happening every 2 to
> > > 10
> > > times.
> > > 
> > > For me, when it fails, it fails the first time when starting to
> > > stream
> > > after rebooting. If it succeeds that first time, it continues to
> > > succeed, until I reboot.
> > 
> > When I read your description I was immediately reminded to this
> > post on
> > NXP forums [1].
> > I do not know if this is what is happening to you, but it sounds
> > somewhat similar. There is also an errata in post [2] describing
> > some
> > backgrounds. Later posts also describe that apparently only CSI
> > port 1
> > is affected, but CSI port 2 is not.
> > Do you have the possibility to test CSI port 2?
> 
> yes but I can only say that csi port 2 behaves better while I have
> seen a lockup there too. That too matches your links' issue
> description. I dont have logs from port 2 yet.
> 
> Thanks a lot, there's at least something new to test I think. Let's
> see whether a kernel thread would work instead of an m4 program.
> 
> But why haven't I ever seen the problem on the mx6s_capture nxp
> driver? That doesn't fit the picture yet for me.
> 
> > 
> > Best regards,
> > Alexander
> > 
> > [1]
> > https://community.nxp.com/t5/i-MX-Processors/IMX8MQ-MIPI-CSI2-Base-address-switching-change-error/m-p/1218063
> > [2]
> > https://community.nxp.com/t5/i-MX-Processors/IMX8MQ-MIPI-CSI2-Base-address-switching-change-error/m-p/1216509/highlight/true#M167970
> > 

this seems to be fixed by
https://lore.kernel.org/linux-media/20211117092710.3084034-1-martin.kepplinger@puri.sm/T/#t

the issue described in the nxp forums should be taken care of by the
underrun (or called "discard" in the nxp driver) buffer in the driver.

thank you!

                                 martin