Am Dienstag, dem 30.11.2021 um 04:33 +0200 schrieb Laurent Pinchart: > Hi Dorota, > > On Mon, Nov 29, 2021 at 05:05:23PM +0100, Dorota Czaplejewicz wrote: > > On Mon, 29 Nov 2021 15:46:11 +0000 Kieran Bingham wrote: > > > Quoting Dorota Czaplejewicz (2021-10-19 12:59:29) > > > > 16-bit bayer formats are used by the i.MX driver. > > > > > > Can we expand upon this at all? > > > > > > The Subject says "Add 16-bit Bayer formats" but this isn't adding > > > the > > > format, it's purely extending the v4l2_format_info table with the > > > information for that format which is otherwise missing. > > > > What do you suggest for a better commit message? My reasoning was > > that > > I'm adding entries to a table. > > The format is defined by V4L2 but isn't present in that table. I'd > state > the this patch is fixing an oversight, and reference the commit that > forgot to add these formats in a Fixes: tag. While at it, I'd also > add > at least the 14bpp Bayer formats, and possibly the packed formats > too. > > > > I wonder what other formats are missing from that table too? > > > > > > > Signed-off-by: Dorota Czaplejewicz < > > > > dorota.czaplejewicz@xxxxxxx > > > > > > > > > --- > > > > Hello, > > > > > > > > While working on the i.MX8 video driver, I discovered that > > > > `v4l2_fill_pixfmt` will fail when using 10-bit sensor formats. > > > > (For background, see the conversation at > > > > https://lkml.org/lkml/2021/10/17/93 > > > > .) > > > > > > > > It appears that the video hardware will fill a 16-bit-per-pixel > > > > buffer when fed 10-bit-per-pixel Bayer data, making > > > > `v4l2_fill_pixfmt` effectively broken for this case. > > > > > > This statement is confusing to me. Are you saying you're > > > programming the > > > hardware with 10 bit, and it's using 16 bits per pixel to store > > > that > > > data? (Which is simply 'unpacked' I think ?) > > > > I know the sensor I'm dealing with sends 10-bit data. I'm observing > > that the data arriving at this stage of the pipeline is encoded > > with > > 16 bits per pixel. As far as I understand, that's what i.MX8 does > > at > > some stage of the MIPI/CSI2 pipeline by design, but I can't > > elaborate > > at the moment, and I don't think it affects the validity of the > > addition. > > Is the 10 bit data stored in the MSB or LSB of the 2 bytes ? Oh, I get a dejavu here. I assume this is on an i.MX8QM or i.MX8QXP, but not one of the other i.MX8 ones. They have a similar name, but are very (!) diffeent in some aspects. To answer your question, neither of those two alignments. The RM for i.MX8QM and i.MX8QXP states: > NOTE > The CSI data is right LSB aligned and zero padded depending > on data format. When interfacing ISI, CSI data is shifted 6-bits > due to ISI bits [5:0] always being zero > (0bxxCSIDATAxxxxxx). All RAW14, RAW12, RAW10, > RAW8, and RAW6 video data is filled from BIT[13] to LSB, > the remaining bits are zero padded. Only RAW16 input data > will be saved to memory from BIT[15] to LSB. See also [1]. This essentially means, unless you use RAW16, you will get RAW14 with a different amount of LSB bits set to 0. IIRC there was some patchset to introduce a RAW14 format ([2]) for exactly this use cas. There is also some kind of demo doing post-processing ([3]). Best regards, Alexander [1] https://community.nxp.com/t5/i-MX-Processors/i-MX8QM-MIPI-Raw-formats-not-working-correctly/m-p/1040832/highlight/true#M153336 [2] https://yhbt.net/lore/all/20200226151431.GY5379@xxxxxxxxxxxxxxxxxxxxxx/T/ [3] https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/i-MX8QXP-capture-raw-bayer-data-and-debayer/ta-p/1098963
