From mboxrd@z Thu Jan  1 00:00:00 1970
From: nicolas.dufresne@gmail.com (Nicolas Dufresne)
Date: Tue, 12 Jul 2016 15:14:02 -0400
Subject: [PATCH v3 3/9] DocBook/v4l: Add compressed video formats used
 on MT8173 codec driver
In-Reply-To: <1468350511.8843.16.camel@gmail.com>
References: <1464611363-14936-1-git-send-email-tiffany.lin@mediatek.com>
 <1464611363-14936-2-git-send-email-tiffany.lin@mediatek.com>
 <1464611363-14936-3-git-send-email-tiffany.lin@mediatek.com>
 <1464611363-14936-4-git-send-email-tiffany.lin@mediatek.com>
 <5a793171-24a7-4e9e-8bfd-f668c789f8e0@xs4all.nl>
 <1468205771.3725.8.camel@mtksdaap41>
 <CAOMLVLiZU3D587dSyp2b2v4DV+MS9vh85bA4BoG7ddK6556rbA@mail.gmail.com>
 <1468350511.8843.16.camel@gmail.com>
Message-ID: <1468350842.8843.18.camel@gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Le mardi 12 juillet 2016 ? 15:08 -0400, Nicolas Dufresne a ?crit?:
> Le mardi 12 juillet 2016 ? 16:16 +0800, Wu-Cheng Li (???) a ?crit?:
> > Decoder hardware produces MT21 (compressed). Image processor can
> > convert it to a format that can be input of display driver.
> > Tiffany.
> > When do you plan to upstream image processor (mtk-mdp)?
> > > 
> > > It can be as input format for encoder, MDP and display drivers in
> > our
> > > platform.
> > I remember display driver can only accept uncompressed MT21. Right?
> > Basically V4L2_PIX_FMT_MT21 is compressed and is like an opaque
> > format. It's not usable until it's decompressed and converted by
> > image
> > processor.
> 
> Previously it was described as MediaTek block mode, and now as a
> MediaTek compressed format. It makes me think you have no idea what
> this pixel format really is. Is that right ?
> 
> The main reason why I keep asking, is that we often find similarities
> between what vendor like to call their proprietary formats. Doing the
> proper research helps not creating a mess like in Android where you
> have a lot of formats that all point to the same format. I believe
> there was the same concern when Samsung wanted to introduce their Z-
> flip-Z NV12 tile format. In the end they simply provided sufficient
> documentation so we could document it and implement software
> converters
> for test and validation purpose.

Here's the kind of information we want in the documentation.

https://chromium.googlesource.com/chromium/src/media/+/master/base/vide
o_types.h#40

? // MediaTek proprietary format. MT21 is similar to NV21 except the memory
? // layout and pixel layout (swizzles). 12bpp with Y plane followed by a 2x2
? // interleaved VU plane. Each image contains two buffers -- Y plane and VU
? // plane. Two planes can be non-contiguous in memory. The starting addresses
? // of Y plane and VU plane are 4KB alignment.
? // Suppose image dimension is (width, height). For both Y plane and VU plane:
? // Row pitch = ((width+15)/16) * 16.
? // Plane size = Row pitch * (((height+31)/32)*32)

Now obviously this is incomplete, as the swizzling need to be documented of course.

> 
> regards,
> Nicolas