Hi Daniel,
On Fri, Jan 24, 2020 at 09:36:25PM +0100, Daniel Glöckner wrote:
> Hello,
>
> the i.MX8QM and i.MX8QXP contain MIPI CSI-2 controllers that forward the
> received data on a parallel bus to the Image Sensing Interface (ISI) of
> the chip. If the data on the MIPI bus is in any of the six RAW formats
> defined for CSI-2, the CSI controller will shift the values so that the
> msb is always in bit 13. This was most likely done to allow following
> hardware to process the data as RAW14 regardless of the actual RAW format.
> Unfortunately the ISI is not able to shift the bits back before writing it
> to memory. RAW8 data therefore has to be saved in two bytes per sample with
> two unused bits at the top and six unused bits at the bottom.
>
> The drivers for the hardware are still being developed in NXP's repository
> at CodeAurora.
Highjacking the thread a little bit, for my information (and thus
without any commitment of any kind), do you know what the upstreaming
plan (and in particular the upstreaming timeline) is ?
> We have extended them to support greyscale and Bayer
> cameras. Now all we need are stable defines for the pixel and media bus
> formats for use in libraries and applications and documentation for people
> to know their meaning.
>
> To keep the number of needed formats low, we would like to ignore that
> there might be unused bits at the bottom. Then we can use the existing
> MEDIA_BUS_FMT_S{BGGR,GBRG,GRBG,RGGB}14_1X14 formats between the CSI
> controller and the ISI and just have to add a MEDIA_BUS_FMT_Y14_1X14
> format. For the pixel formats we would add V4L2_PIX_FMT_Y14 and rebase
> e38d5f254ad8 from Sakari's packed12-postponed branch for Bayer.
>
> Now the questions:
>
> - Is it acceptable to use MEDIA_BUS_FMT_Y14_1X14 in this case instead of
> using MEDIA_BUS_FMT_Y12_1X14_PADLO, MEDIA_BUS_FMT_Y10_1X14_PADLO,
> MEDIA_BUS_FMT_Y8_1X14_PADLO, MEDIA_BUS_FMT_Y7_1X14_PADLO,
> MEDIA_BUS_FMT_Y6_1X14_PADLO? Another 20 _PADLO formats would have to
> be added for Bayer.
>
> - Given the history of Sakari's packed12-postponed branch, is there a
> chance to get these definitions merged into mainline although the
> driver is not? I fear that NXP's drivers will not hit mainline for a
> long time.
>
> - Sakari, do you mind me adding the same license header to your
> pixfmt-y14.rst that is used by all other pixfmt-y*.rst files?
--
Regards,
Laurent Pinchart
