On Tue 31 July 2012 13:17:50 Sakari Ailus wrote: > Hi Hans and Laurent, > > On Mon, Jul 30, 2012 at 09:19:13PM +0200, Hans Verkuil wrote: > > On Mon July 30 2012 21:06:33 Laurent Pinchart wrote: > > > Hi Hans, > > > > > > On Monday 30 July 2012 20:36:36 Hans Verkuil wrote: > > > > On Sat July 28 2012 00:01:24 Sakari Ailus wrote: > > > > > On Fri, Jul 27, 2012 at 04:25:04PM +0530, Prabhakar Lad wrote: > > > > > > From: Manjunath Hadli <manjunath.hadli@xxxxxx> > > > > > > > > > > > > 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.pinchart@xxxxxxxxxxxxxxxx> > > > > > > Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > > > > > Signed-off-by: Manjunath Hadli <manjunath.hadli@xxxxxx> > > > > > > Signed-off-by: Lad, Prabhakar <prabhakar.lad@xxxxxx> > > > > > > Cc: Sakari Ailus <sakari.ailus@xxxxxx> > > > > > > Cc: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> > > > > > > --- > > > > > > > > > > > > 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. > > One should use the pixel format field for that. Besides, dummy bits can be > anything; the user shoudn't expect a particular fixed value. That'd make the > application specific to that device. It's used for debugging: by giving dummy fields a non-zero fixed value they are easy to identify when doing a memory dump. > > > > 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. > > > > > > On the other hand, when you process data that includes dummy bits stored in > > > memory, knowing that the dummy bits are zero can save a mask operation. > > > > > > I don't have a strong opinion whether we should use zero or dummy bits for > > > media bus formats. For memory formats I'd be inclined to use zero bits (at > > > least when capturing). > > > > And make a new pixel format if you have hardware that doesn't use zero? I think > > it's overkill IMHO. > > Could be. But I've seen only zero being used. > > Applications that need to process raw bayer images optimally are often very > hardware specific anyway, adding the assumption that the dummy bits are zero > isn't a big deal. The same might not apply as universally to yuv colour > space but on the other hand one extra and operation just won't take that > much time either. My experience is with encoders and decoders. Anyway, we're not using this format, and neither will we ever upstream a pixel or mbus format since it is all highly specific to our products, so there is no point in upstreaming. So I am actually OK with saying that these bits should be 0, provided 'D' is replaced by 'Z'. But I still think keeping it 'D' and allowing for any value is more generic and I expect that it is sufficient. > I'm fine with defining the bits are dummy. I just wanted we make an informed > decision on this, and as far as I see that's now been reached. > > Acked-by: Sakari Ailus <sakari.ailus@xxxxxx> OK, then we all agree to keep PATCHv7 as is? Regards, Hans > > Kind regards, > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
