[PATCH] media: hantro: Check whether reset op is defined before use

[Marek Vasut]

On 8/24/23 12:39, Adam Ford wrote:
> On Wed, Aug 23, 2023 at 8:39 PM Marek Vasut <marex at denx.de> wrote:
>>
>> The i.MX8MM/N/P does not define the .reset op since reset of the VPU is
>> done by genpd. Check whether the .reset op is defined before calling it
>> to avoid NULL pointer dereference.
>>
>> Note that the Fixes tag is set to the commit which removed the reset op
>> from i.MX8M Hantro G2 implementation, this is because before this commit
>> all the implementations did define the .reset op.
> 
> I am surprised I didn't have issues when I was testing the 8MQ and
> 8MM, but this makes sense.

You need to trigger the VPU watchdog to trigger the crash, that means 
you have to get the VPU into some weird state where it fails to decode 
frame. Then it triggers the reset and ... boom.

See this patch, that contains a gstreamer invocation to generate such 
trigger condition input data:

[PATCH] media: verisilicon: Do not enable G2 postproc downscale if 
source is narrower than destination

"
To generate input test data to trigger this bug, use e.g.:
$ gst-launch-1.0 videotestsrc ! 
video/x-raw,width=272,height=256,format=I420 ! \
                  vp9enc ! matroskamux ! filesink location=/tmp/test.vp9
To trigger the bug upon decoding (note that the NV12 must be forced, as
that assures the output data would pass the G2 postproc):
$ gst-launch-1.0 filesrc location=/tmp/test.vp9 ! matroskademux ! 
vp9parse ! \
                  v4l2slvp9dec ! video/x-raw,format=NV12 ! videoconvert 
! fbdevsink
"