linux-kernel - Re: [PATCH v7 2/4] media: videodev2: add V4L2_FMT_FLAG_FIXED

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Message-ID: <1560243127.13886.3.camel@pengutronix.de>
Date:   Tue, 11 Jun 2019 10:52:07 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Maxime Jourdan <mjourdan@...libre.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>
Cc:     Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org
Subject: Re: [PATCH v7 2/4] media: videodev2: add
 V4L2_FMT_FLAG_FIXED_RESOLUTION

On Wed, 2019-06-05 at 15:39 +0200, Hans Verkuil wrote:
> Hi Maxime,
> 
> I am wondering if this flag shouldn't be inverted: you set
> V4L2_FMT_FLAG_DYN_RESOLUTION if dynamic resolution is supported,
> otherwise it isn't.
> 
> Can all the existing mainlined codec drivers handle midstream
> resolution changes?
> 
> s5p-mfc, venus and mediatek can, but I see no SOURCE_CHANGE event in
> the coda drivers, so I suspect that that can't handle this.
> 
> Philipp, what is the status of the coda driver for dynamic resolution
> changes?

FTR, to my knowledge there is no dynamic resolution change support in
the firmware, as there is no signal (interrupt nor picture run return
value) to indicate that different headers were parsed.

I am planning to add the initial source change event required by the
current decoder API documentation, but I am afraid there will be no
support for source changes due to mid-stream resolution changes due to
firmware limitations.

regards
Philipp