On Sat July 28 2012 00:01:24 Sakari Ailus wrote:
> Hi Prabhakar,
>
> Thanks for the patch, and my apologies for delayed answer!
>
> On Fri, Jul 27, 2012 at 04:25:04PM +0530, Prabhakar Lad wrote:
> > From: Manjunath Hadli <manjunath.ha...@ti.com>
> >
> > add new enum entries for supporting the media-bus formats on dm365.
> > These include some bayer and some non-bayer formats.
> > V4L2_MBUS_FMT_YDYUYDYV8_1X16 and V4L2_MBUS_FMT_UV8_1X8 are used
> > internal to the hardware by the resizer.
> > V4L2_MBUS_FMT_SBGGR10_ALAW8_1X8 represents the bayer ALAW format
> > that is supported by dm365 hardware.
> >
> > Acked-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> > Acked-by: Hans Verkuil <hans.verk...@cisco.com>
> > Signed-off-by: Manjunath Hadli <manjunath.ha...@ti.com>
> > Signed-off-by: Lad, Prabhakar <prabhakar....@ti.com>
> > Cc: Sakari Ailus <sakari.ai...@iki.fi>
> > Cc: Guennadi Liakhovetski <g.liakhovet...@gmx.de>
> > ---
> > Documentation/DocBook/media/v4l/subdev-formats.xml | 250
> > +++++++++++++++++++-
> > include/linux/v4l2-mediabus.h | 10 +-
> > 2 files changed, 252 insertions(+), 8 deletions(-)
> >
> > diff --git a/Documentation/DocBook/media/v4l/subdev-formats.xml
> > b/Documentation/DocBook/media/v4l/subdev-formats.xml
> > index 49c532e..75dc275 100644
> > --- a/Documentation/DocBook/media/v4l/subdev-formats.xml
> > +++ b/Documentation/DocBook/media/v4l/subdev-formats.xml
> > @@ -353,9 +353,9 @@
> > <listitem><para>The number of bits per pixel component. All components
> > are
> > transferred on the same number of bits. Common values are 8, 10 and
> > 12.</para>
> > </listitem>
> > - <listitem><para>If the pixel components are DPCM-compressed, a mention
> > of the
> > - DPCM compression and the number of bits per compressed pixel
> > component.</para>
> > - </listitem>
> > + <listitem><para>The compression (optional). If the pixel components are
> > + ALAW- or DPCM-compressed, a mention of the compression scheme and the
> > + number of bits per compressed pixel component.</para></listitem>
> > <listitem><para>The number of bus samples per pixel. Pixels that are
> > wider than
> > the bus width must be transferred in multiple samples. Common values are
> > 1 and 2.</para></listitem>
> > @@ -504,6 +504,74 @@
> > <entry>r<subscript>1</subscript></entry>
> > <entry>r<subscript>0</subscript></entry>
> > </row>
> > + <row id="V4L2-MBUS-FMT-SBGGR10-ALAW8-1X8">
> > + <entry>V4L2_MBUS_FMT_SBGGR10_ALAW8_1X8</entry>
> > + <entry>0x3015</entry>
> > + <entry></entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>b<subscript>7</subscript></entry>
> > + <entry>b<subscript>6</subscript></entry>
> > + <entry>b<subscript>5</subscript></entry>
> > + <entry>b<subscript>4</subscript></entry>
> > + <entry>b<subscript>3</subscript></entry>
> > + <entry>b<subscript>2</subscript></entry>
> > + <entry>b<subscript>1</subscript></entry>
> > + <entry>b<subscript>0</subscript></entry>
> > + </row>
> > + <row id="V4L2-MBUS-FMT-SGBRG10-ALAW8-1X8">
> > + <entry>V4L2_MBUS_FMT_SGBRG10_ALAW8_1X8</entry>
> > + <entry>0x3016</entry>
> > + <entry></entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>g<subscript>7</subscript></entry>
> > + <entry>g<subscript>6</subscript></entry>
> > + <entry>g<subscript>5</subscript></entry>
> > + <entry>g<subscript>4</subscript></entry>
> > + <entry>g<subscript>3</subscript></entry>
> > + <entry>g<subscript>2</subscript></entry>
> > + <entry>g<subscript>1</subscript></entry>
> > + <entry>g<subscript>0</subscript></entry>
> > + </row>
> > + <row id="V4L2-MBUS-FMT-SGRBG10-ALAW8-1X8">
> > + <entry>V4L2_MBUS_FMT_SGRBG10_ALAW8_1X8</entry>
> > + <entry>0x3017</entry>
> > + <entry></entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>g<subscript>7</subscript></entry>
> > + <entry>g<subscript>6</subscript></entry>
> > + <entry>g<subscript>5</subscript></entry>
> > + <entry>g<subscript>4</subscript></entry>
> > + <entry>g<subscript>3</subscript></entry>
> > + <entry>g<subscript>2</subscript></entry>
> > + <entry>g<subscript>1</subscript></entry>
> > + <entry>g<subscript>0</subscript></entry>
> > + </row>
> > + <row id="V4L2-MBUS-FMT-SRGGB10-ALAW8-1X8">
> > + <entry>V4L2_MBUS_FMT_SRGGB10_ALAW8_1X8</entry>
> > + <entry>0x3018</entry>
> > + <entry></entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>-</entry>
> > + <entry>r<subscript>7</subscript></entry>
> > + <entry>r<subscript>6</subscript></entry>
> > + <entry>r<subscript>5</subscript></entry>
> > + <entry>r<subscript>4</subscript></entry>
> > + <entry>r<subscript>3</subscript></entry>
> > + <entry>r<subscript>2</subscript></entry>
> > + <entry>r<subscript>1</subscript></entry>
> > + <entry>r<subscript>0</subscript></entry>
> > + </row>
> > <row id="V4L2-MBUS-FMT-SBGGR10-DPCM8-1X8">
> > <entry>V4L2_MBUS_FMT_SBGGR10_DPCM8_1X8</entry>
> > <entry>0x300b</entry>
> > @@ -853,10 +921,16 @@
> > <title>Packed YUV Formats</title>
> >
> > <para>Those data formats transfer pixel data as (possibly
> > downsampled) Y, U
> > - and V components. The format code is made of the following
> > information.
> > + and V components. Some formats include dummy bits in some of their
> > samples
> > + and are collectively referred to as "YDYC" (Y-Dummy-Y-Chroma)
> > formats.
> > + One cannot rely on the values of these dummy bits as those are
> > undefined.
> > + </para>
> > + <para>The format code is made of the following information.
> > <itemizedlist>
> > <listitem><para>The Y, U and V components order code, as transferred on
> > the
> > - bus. Possible values are YUYV, UYVY, YVYU and VYUY.</para></listitem>
> > + bus. Possible values are YUYV, UYVY, YVYU and VYUY for formats with no
> > + dummy bit, and YDYUYDYV, YDYVYDYU, YUYDYVYD and YVYDYUYD for YDYC
> > formats.
> > + </para></listitem>
> > <listitem><para>The number of bits per pixel component. All components
> > are
> > transferred on the same number of bits. Common values are 8, 10 and
> > 12.</para>
> > </listitem>
>
> I dicussed dummy vs. padding (zeros) with Laurent and we concluded we should
> use zero padding instead. The difference is that when processing the pixels
> no extra operations are necessary to get rid of the dummy data when the
> dummy bits are actually zero --- which in practice always is the case.
>
> I'm not aware of hardware that would assign padding bits (in this very
> purpose) that are a part of writes the width of bus width something else
> than zeros. It wouldn't make much sense either.
>
> So I suggest that dummy is replaced by padding which is defined to be zero.
>
> The letter in the format name could be 'Z', for example.
>
> Hans: what do you think?
Bad idea. First of all, some hardware or FPGA can insert different values there.
It's something that Cisco uses in some cases: it makes it easier to identify the
dummy values if they have a non-zero fixed value.
Another reason for not doing this is when such formats are used to display
video:
you don't want to force the software to fill in the dummy values with a specific
value for no good reason. That would only cost extra CPU cycles.
Regards,
Hans
>
> Kind regards,
>
>
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