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Date:   Tue, 8 Oct 2019 14:33:38 +0300
From:   Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
To:     "sandy.huang" <hjc@rock-chips.com>
Cc:     dri-devel@lists.freedesktop.org,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <maxime.ripard@bootlin.com>,
        Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/3] drm: Add some new format DRM_FORMAT_NVXX_10
Message-ID: <20191008113338.GP1208@intel.com>
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 <20190930104849.GA1208@intel.com>
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On Tue, Oct 08, 2019 at 10:40:20AM +0800, sandy.huang wrote:
> Hi ville syrjala,
> 
> 在 2019/9/30 下午6:48, Ville Syrjälä 写道:
> > On Thu, Sep 26, 2019 at 04:24:47PM +0800, Sandy Huang wrote:
> >> These new format is supported by some rockchip socs:
> >>
> >> DRM_FORMAT_NV12_10/DRM_FORMAT_NV21_10
> >> DRM_FORMAT_NV16_10/DRM_FORMAT_NV61_10
> >> DRM_FORMAT_NV24_10/DRM_FORMAT_NV42_10
> >>
> >> Signed-off-by: Sandy Huang <hjc@rock-chips.com>
> >> ---
> >>   drivers/gpu/drm/drm_fourcc.c  | 18 ++++++++++++++++++
> >>   include/uapi/drm/drm_fourcc.h | 14 ++++++++++++++
> >>   2 files changed, 32 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> >> index c630064..ccd78a3 100644
> >> --- a/drivers/gpu/drm/drm_fourcc.c
> >> +++ b/drivers/gpu/drm/drm_fourcc.c
> >> @@ -261,6 +261,24 @@ const struct drm_format_info *__drm_format_info(u32 format)
> >>   		{ .format = DRM_FORMAT_P016,		.depth = 0,  .num_planes = 2,
> >>   		  .char_per_block = { 2, 4, 0 }, .block_w = { 1, 0, 0 }, .block_h = { 1, 0, 0 },
> >>   		  .hsub = 2, .vsub = 2, .is_yuv = true},
> >> +		{ .format = DRM_FORMAT_NV12_10,		.depth = 0,  .num_planes = 2,
> >> +		  .char_per_block = { 5, 10, 0 }, .block_w = { 4, 4, 0 }, .block_h = { 4, 4, 0 },
> >> +		  .hsub = 2, .vsub = 2, .is_yuv = true},
> >> +		{ .format = DRM_FORMAT_NV21_10,		.depth = 0,  .num_planes = 2,
> >> +		  .char_per_block = { 5, 10, 0 }, .block_w = { 4, 4, 0 }, .block_h = { 4, 4, 0 },
> >> +		  .hsub = 2, .vsub = 2, .is_yuv = true},
> >> +		{ .format = DRM_FORMAT_NV16_10,		.depth = 0,  .num_planes = 2,
> >> +		  .char_per_block = { 5, 10, 0 }, .block_w = { 4, 4, 0 }, .block_h = { 4, 4, 0 },
> >> +		  .hsub = 2, .vsub = 1, .is_yuv = true},
> >> +		{ .format = DRM_FORMAT_NV61_10,		.depth = 0,  .num_planes = 2,
> >> +		  .char_per_block = { 5, 10, 0 }, .block_w = { 4, 4, 0 }, .block_h = { 4, 4, 0 },
> >> +		  .hsub = 2, .vsub = 1, .is_yuv = true},
> >> +		{ .format = DRM_FORMAT_NV24_10,		.depth = 0,  .num_planes = 2,
> >> +		  .char_per_block = { 5, 10, 0 }, .block_w = { 4, 4, 0 }, .block_h = { 4, 4, 0 },
> >> +		  .hsub = 1, .vsub = 1, .is_yuv = true},
> >> +		{ .format = DRM_FORMAT_NV42_10,		.depth = 0,  .num_planes = 2,
> >> +		  .char_per_block = { 5, 10, 0 }, .block_w = { 4, 4, 0 }, .block_h = { 4, 4, 0 },
> >> +		  .hsub = 1, .vsub = 1, .is_yuv = true},
> >>   		{ .format = DRM_FORMAT_P210,		.depth = 0,
> >>   		  .num_planes = 2, .char_per_block = { 2, 4, 0 },
> >>   		  .block_w = { 1, 0, 0 }, .block_h = { 1, 0, 0 }, .hsub = 2,
> >> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> >> index 3feeaa3..08e2221 100644
> >> --- a/include/uapi/drm/drm_fourcc.h
> >> +++ b/include/uapi/drm/drm_fourcc.h
> >> @@ -238,6 +238,20 @@ extern "C" {
> >>   #define DRM_FORMAT_NV42		fourcc_code('N', 'V', '4', '2') /* non-subsampled Cb:Cr plane */
> >>   
> >>   /*
> >> + * 2 plane YCbCr
> >> + * index 0 = Y plane, Y3:Y2:Y1:Y0 10:10:10:10
> >> + * index 1 = Cb:Cr plane, Cb3:Cr3:Cb2:Cr2:Cb1:Cr1:Cb0:Cr0 10:10:10:10:10:10:10:10
> >> + * or
> >> + * index 1 = Cr:Cb plane, Cr3:Cb3:Cr2:Cb2:Cr1:Cb1:Cr0:Cb0 10:10:10:10:10:10:10:10
> > So now you're defining it as some kind of byte aligned block.
> > With that specifying endianness would now make sense since
> > otherwise this tells us absolutely nothing about the memory
> > layout.
> >
> > So I'd either do that, or go back to not specifying anything and
> > use some weasel words like "mamory layout is implementation defined"
> > which of course means no one can use it for anything that involves
> > any kind of cross vendor stuff.
> /*
>   * 2 plane YCbCr
>   * index 0 = Y plane, [39: 0] Y3:Y2:Y1:Y0 10:10:10:10  little endian
>   * index 1 = Cb:Cr plane, [79: 0] Cb3:Cr3:Cb2:Cr2:Cb1:Cr1:Cb0:Cr0 
> 10:10:10:10:10:10:10:10  little endian
>   * or
>   * index 1 = Cr:Cb plane, [79: 0] Cr3:Cb3:Cr2:Cb2:Cr1:Cb1:Cr0:Cb0 
> 10:10:10:10:10:10:10:10  little endian
>   */
> 
> Is this description ok?

Seems OK to me, if it actually describes the format correctly.

Though I'm not sure why the CbCr is defines as an 80bit block
and Y has a 40bit block. 40bits should be enough for CbCr as well.

> 
> >> + */
> >> +#define DRM_FORMAT_NV12_10	fourcc_code('N', 'A', '1', '2') /* 2x2 subsampled Cr:Cb plane */
> >> +#define DRM_FORMAT_NV21_10	fourcc_code('N', 'A', '2', '1') /* 2x2 subsampled Cb:Cr plane */
> >> +#define DRM_FORMAT_NV16_10	fourcc_code('N', 'A', '1', '6') /* 2x1 subsampled Cr:Cb plane */
> >> +#define DRM_FORMAT_NV61_10	fourcc_code('N', 'A', '6', '1') /* 2x1 subsampled Cb:Cr plane */
> >> +#define DRM_FORMAT_NV24_10	fourcc_code('N', 'A', '2', '4') /* non-subsampled Cr:Cb plane */
> >> +#define DRM_FORMAT_NV42_10	fourcc_code('N', 'A', '4', '2') /* non-subsampled Cb:Cr plane */
> >> +
> >> +/*
> >>    * 2 plane YCbCr MSB aligned
> >>    * index 0 = Y plane, [15:0] Y:x [10:6] little endian
> >>    * index 1 = Cr:Cb plane, [31:0] Cr:x:Cb:x [10:6:10:6] little endian
> >> -- 
> >> 2.7.4
> >>
> >>
> >>
> >> _______________________________________________
> >> dri-devel mailing list
> >> dri-devel@lists.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

-- 
Ville Syrjälä
Intel