[PATCH libdrm] libdrm: update drm/drm_fourcc.h from kernel to add multi plane formats

daeinki at gmail.com daeinki at gmail.com
Fri Apr 6 23:01:49 PDT 2012

나의 iPad에서 보냄

2012. 4. 6. 오후 4:43 Ville Syrjälä <syrjala at sci.fi> 작성:

> On Fri, Apr 06, 2012 at 03:05:36PM +0900, Inki Dae wrote:
>> Hi Ville,
>>> -----Original Message-----
>>> From: Ville Syrjälä [mailto:ville.syrjala at linux.intel.com]
>>> Sent: Friday, April 06, 2012 3:14 AM
>>> To: airlied at redhat.com
>>> Cc: inki.dae at samsung.com; kyungmin.park at samsung.com; dri-
>>> devel at lists.freedesktop.org; Seung-Woo Kim
>>> Subject: Re: [PATCH libdrm] libdrm: update drm/drm_fourcc.h from kernel to
>>> add multi plane formats
>>> On Fri, Mar 30, 2012 at 01:12:58PM +0300, 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.kim at 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.
>>> And I just realized that I was already too late with my NAK since this a
>>> libdrm patch. Apparently the kernel drm_fourcc.h changes were snuck in
>>> via some backdoor without review. Sigh.
>> We had already requested review for it. for this you can refer to link
>> below:
>> http://lists.freedesktop.org/archives/dri-devel/2011-December/017654.html
> I see. I couldn't find it in my work mailbox for some reason, and I
> don't remember having seen the patch before. I suppose I just missed it
> due to Christmas vacations, and was too blind to see it in my mailbox.
> Also google decicded to filter my search results too much, so I didn't
> spot it via the web archives either. I'm sorry for the false accusation.
>>> So they're now in Linus's tree. But looks like format_check() was never
>>> updated to accept them, so there's no way anyone could actually be using
>>> them. So Dave, can we still remove them from the kernel header?
>> Yes, right. these formats aren't used for any SoCs except Exynos series yet
>> but just we are first. I think they should be added because anyone may use
>> them someday at least possible.
> Since DRM_FORMAT_NV12M is _identical_ to DRM_FORMAT_NV12, I see no point
> in adding it (similarly for YUV420M vs. YUV420).

but with this way,  user and device driver should understand NV12M format and how gem handles should send to driver and also how the driver should decide whether these handles mean NV12M or NV12. I think these things are unnecessary codes. with such theory, maybe current some fourcc formats couldn't be removed because we can identify desired format if we add some codes for it. as you mentioned, it's important to avoid such duplicated formats but also to consider user and device driver. so I think it's not good for user and driver should understand and decide them. Please give me your opinion.

Inki Dae

> -- 
> Ville Syrjälä
> syrjala at sci.fi
> http://www.sci.fi/~syrjala/
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