Hi Ville,

I skipped explanation about NV12M and other two formats because these
formats are already in kernel drm_fourcc.h.

I think it is better to add a difference between NV12 and NV12M here.

NV12M has Y plane and CbCr plane and these are in non contiguous memory
region. Compared with NV12, NV12M's memory shape is like following.
NV12  : ______(Y)(CbCr)_______
NV12M : __(Y)_ ..... _(CbCr)__

Y and CbCr plane of NV12 can be expressed with one memory address and
offset of each plane. but NV12M needs memory address of each plane.

On 2012년 03월 30일 19:12, Ville Syrjälä wrote:
On Fri, Mar 30, 2012 at 11:54:50AM +0900, Seung-Woo Kim wrote:
Multi buffer plane pixel formats are added as like kernel header.

Signed-off-by: Seung-Woo Kim<sw0312....@samsung.com>
---
  include/drm/drm_fourcc.h |    7 +++++++
  1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 85facb0..7cfd95a 100644
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -107,6 +107,10 @@
  #define DRM_FORMAT_NV16               fourcc_code('N', 'V', '1', '6') /* 2x1 
subsampled Cr:Cb plane */
  #define DRM_FORMAT_NV61               fourcc_code('N', 'V', '6', '1') /* 2x1 
subsampled Cb:Cr plane */

+/* 2 non contiguous plane YCbCr */
+#define DRM_FORMAT_NV12M       fourcc_code('N', 'M', '1', '2') /* 2x2 
subsampled Cr:Cb plane */
NAK. DRM_FORMAT_NV12 handles this just fine.


Exynos soc supports two kinds of memory shape explained above, so two
different types are need for exynos soc.

+#define DRM_FORMAT_NV12MT      fourcc_code('T', 'M', '1', '2') /* 2x2 
subsampled Cr:Cb plane 64x32 macroblocks */
This one is more difficult. Until now tiling was always handled in
driver specific manner. OTOH if this format is really supported by
different devices from multiple vendors, then it would probably
make sense to add it as a standard format.

Exynos soc also supports normal and tiled pixel data and pixel data is shared
between hw blocks for example from scaler to hdmi.
So driver can not handle it internally.

IMHO, support for various shape can be helpful even though only exynos soc
family suppors these formats currently.

+
  /*
   * 3 plane YCbCr
   * index 0: Y plane, [7:0] Y
@@ -127,4 +131,7 @@
  #define DRM_FORMAT_YUV444     fourcc_code('Y', 'U', '2', '4') /* 
non-subsampled Cb (1) and Cr (2) planes */
  #define DRM_FORMAT_YVU444     fourcc_code('Y', 'V', '2', '4') /* 
non-subsampled Cr (1) and Cb (2) planes */

+/* 3 non contiguous plane YCbCr */
+#define DRM_FORMAT_YUV420M     fourcc_code('Y', 'M', '1', '2') /* 2x2 
subsampled Cb (1) and Cr (2) planes */a
NAK. DRM_FORMAT_YUV420 handles this.

This is same with case of NV12M.

Regards.

--
Seung-Woo Kim
Samsung Software R&D Center
--


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