linux-kernel - Re: [PATCH 2/2] drm/msm: Support NV12MT format in mdp4

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Message-ID: <82b1d9a983a2d2fc01414022775e3e43.squirrel@www.codeaurora.org>
Date:	Fri, 13 Mar 2015 09:51:11 -0500
From:	"Stéphane Viau" <sviau@...eaurora.org>
To:	"Daniel Vetter" <daniel@...ll.ch>
Cc:	"Beeresh Gopal" <gbeeresh@...eaurora.org>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
	"dri-devel" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH 2/2] drm/msm: Support NV12MT format in mdp4

Hi Daniel,

> On Fri, Feb 20, 2015 at 3:42 PM, Beeresh Gopal <gbeeresh@...eaurora.org>
> wrote:
>> +/* Samsung framebuffer modifiers */
>> +
>> +/*
>> + * NV12 64x32 Tiled
>> + *
>> + * 2 planes Y and CbCr, grouped into 64x32 macro tiles,
>> + * with a non-standard order in memory (Z-shape).
>> + *
>> + * Pixel layout identical to DRM_FORMAT_NV21 format:
>> + * index 0 = Y plane, [7:0] Y
>> + * index 1 = Cb:Cr plane, [15:0] Cb:Cr little endian
>> + */
>> +#define DRM_FORMAT_MOD_SAMSUNG_64_32_TILE fourcc_mod_code(SAMSUNG, 1)
>
> This description mixes layout information with pixel format. Strictly
> speaking you could use this for other formats, but since the
> description doesn't mention whether this is in bytes or pixels that's
> a bit awkward. Or just mandatae that this can only be used with NV12
> fourcc (and maybe add a check for that into the core drm code.

Agreed: I think /* Tiled: 64x32 pixel macroblocks */ - or something along
those lines - as a description should do the trick.

>
> Also, is this really samsung and not mpeg?

>From my understanding the VENDOR is actually SAMSUNG for the following
reasons:
 a) V4L2_PIX_FMT_NV12MT has  been introduced[1] for the Samsungs s5p-fimc
driver (which got renamed into exynos4-is[2])
 b) A search on V4L2_PIX_FMT_NV12MT in the drivers folder only returns
Samsung drivers so far..

[1]
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4a3c9b4f0df43207eb0b4d0da9cb51e185506bd5
[2]
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=56fa1a6a6a7da91e7ece8b01b0ae8adb2926e434

> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>

Stéphane
-- 
Qualcomm Innovation Center, Inc.

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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