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Subject: Re: [EXT] Re: [PATCH 0/5] Add V4L2 driver for i.MX8 JPEG
 Encoder/Decoder
To:     Mirela Rabulea <mirela.rabulea@nxp.com>,
        "mchehab@kernel.org" <mchehab@kernel.org>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>
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        "laurent.pinchart+renesas@ideasonboard.com" 
        <laurent.pinchart+renesas@ideasonboard.com>,
        Aisheng Dong <aisheng.dong@nxp.com>,
        Laurentiu Palcu <laurentiu.palcu@nxp.com>,
        "paul.kocialkowski@bootlin.com" <paul.kocialkowski@bootlin.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
        Robert Chiras <robert.chiras@nxp.com>,
        "mark.rutland@arm.com" <mark.rutland@arm.com>,
        "p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
        "niklas.soderlund+renesas@ragnatech.se" 
        <niklas.soderlund+renesas@ragnatech.se>,
        Daniel Baluta <daniel.baluta@nxp.com>,
        Leonard Crestez <leonard.crestez@nxp.com>,
        "dafna.hirschfeld@collabora.com" <dafna.hirschfeld@collabora.com>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        Nicolas Dufresne <nicolas@ndufresne.ca>
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From:   Hans Verkuil <hverkuil-cisco@xs4all.nl>
Message-ID: <ffbc7501-bb56-b5f2-cd43-209f099be594@xs4all.nl>
Date:   Fri, 8 Nov 2019 15:06:25 +0100
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On 11/8/19 2:36 PM, Mirela Rabulea wrote:
> Hi Hans,
> 
> On Mi, 2019-11-06 at 17:52 +0100, Hans Verkuil wrote:
>>       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:
>>>       test VIDIOC_(TRY_)ENCODER_CMD: OK
>> The presence of this...
>>
>>>
>>>       test VIDIOC_G_ENC_INDEX: OK (Not Supported)
>>>       test 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:
>>>       test read/write: OK (Not Supported)
>>>       test blocking wait: OK
>>>               fail: 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