Re: [EXT] Re: [PATCH 0/5] Add V4L2 driver for i.MX8 JPEG Encoder/Decoder

[Hans Verkuil]

On 11/8/19 2:36 PM, Mirela Rabulea wrote:
> Hi Hans,
> 
> On Mi, 2019-11-06 at 17:52 +0100, Hans Verkuil wrote:
>> Â Â Â test Scaling: OK
>> The presence of a scaler is suspicious: is the encoder indeed
>> capable of scaling? I suspect this is a bug.
> 
> No, it's not capable of scaling. You suspect a bug in the driver or the
> tests?

Actually, I think that's an outstanding bug in v4l-utils. It doesn't
correctly handle the m2m case with respect to scaling. I think. I'll
look into this a bit more.

> 
>> Codec ioctls:
>>> ÂÂÂÂÂÂtest VIDIOC_(TRY_)ENCODER_CMD: OK
>> The presence of this...
>>
>>>
>>> ÂÂÂÂÂÂtest VIDIOC_G_ENC_INDEX: OK (Not Supported)
>>> ÂÂÂÂÂÂtest VIDIOC_(TRY_)DECODER_CMD: OK
>> ...and this is also strange for a JPEG codec. These ioctls are
>> typically only
>> needed for MPEG/H264/etc. codecs, and not for a simple JPEG codec.
>>
>> The same issues are found for the JPEG decoder.
> 
> I implemented the CMD_STOP for both encoder & decoder, because it was
> requested by our developer for gstreamer plugin for this codec.
> The context in which this was requested was for playing MJPEG videos (a
> concatenation of JPEG frames).

This ioctl makes no sense for JPEG codecs, and in fact jpeg drivers like
s5p-jpeg or mtk-jpeg do not implement this. This sounds like a gstreamer bug.
Nicolas, do you know anything about this?

> 
>> Streaming ioctls:
>>> ÂÂÂÂÂÂtest read/write: OK (Not Supported)
>>> ÂÂÂÂÂÂtest blocking wait: OK
>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂfail: v4l2-test-buffers.cpp(254): g_field() ==
>>> V4L2_FIELD_ANY
>> The driver shall never return FIELD_ANY. This needs to be FIELD_NONE.
> 
> Is there a "good example" of a v4l m2m driver that passes these

vim2m. Also drivers/media/platform/mtk-jpeg/ (although I'm not sure when
it was last tested with v4l2-compliance, so it might be a bit out of date).

> streaming tests? That would save some time on my side.
> For the FIELD_ANY issue, I got inspired from your commit:
> ab7afaf3 media: vim2m: add buf_out_validate callback
> But there's a lot more to go...
> 
> Thanks,
> Mirela
> 

Regards,

	Hans