[PATCH 0/3] Adding new drm formats needed by Xilinx IPs

[Emil Velikov]

On 28 November 2017 at 17:26, Hyun Kwon <hyunk at xilinx.com> wrote:
>
>
>> -----Original Message-----
>> From: Emil Velikov [mailto:emil.l.velikov at gmail.com]
>> Sent: Tuesday, November 28, 2017 7:02 AM
>> To: Daniel Vetter <daniel at ffwll.ch>
>> Cc: Hyun Kwon <hyunk at xilinx.com>; monstr at monstr.eu; David Airlie
>> <airlied at linux.ie>; ML dri-devel <dri-devel at lists.freedesktop.org>; Daniel
>> Vetter <daniel.vetter at intel.com>; Jeff Mouroux <jmouroux at xilinx.com>;
>> Satish Kumar Nagireddy <SATISHNA at xilinx.com>; Laurent Pinchart
>> <laurent.pinchart at ideasonboard.com>
>> Subject: Re: [PATCH 0/3] Adding new drm formats needed by Xilinx IPs
>>
>> On 28 November 2017 at 11:09, Daniel Vetter <daniel at ffwll.ch> wrote:
>> > On Mon, Nov 27, 2017 at 06:27:30PM -0800, Hyun Kwon wrote:
>> >> Hi,
>> >>
>> >> This series is to add new drm formats needed by some Xilinx IPs.
>> >> Some formats have unique characteristics such as pixels not being
>> >> byte-aligned. For instance, some 10bit formats have 2bit padding
>> >> after every 3-10bit components:
>> >>
>> >>       32b[0]: 10b comp0 - 10b comp1 - 10b comp2 - 2b padding
>> >>       32b[1]: 10b comp3 - 10b comp4 - 10b comp5 - 2b padding
>> >>       ...
>> >>
>> >> To model this, additional information is added to struct
>> drm_format_info.
>> >> The patch has been tested with downstream drivers as well as the
>> downstream
>> >> user space component (ex, modified modetest).
>> >>
>> >> Thanks,
>> >> hyun
>> >>
>> >> Jeffrey Mouroux (2):
>> >>   uapi: drm: New fourcc codes needed by Xilinx Video IP
>> >>   drm: fourcc: Update DRM Framework with new fourcc codes
>> >>
>> >> Satish Kumar Nagireddy (1):
>> >>   drm: drm_fourcc: Add scaling and padding factor to drm_format_info
>> >
>> > We need the driver for this.
>>
>> To elaborate this in different light:
>> Without an upstream user (both kernel and userspace) this will be in a
>> perpetual broken state.
>> If the Xilinx DRM driver is still far off, one could update any of the
>> existing drivers - say i915 :-P
>
> Fair enough. This patch will have to wait until any client code can be upstreamed along with.
>
Humble suggestion: try to upstream the basic functionality of your
driver as early as possible.
DRM evolves rapidly, so any lingering work will require serious work
to rebase and ensure it works.

Quick skim at the Xilinx repository shows that initial work was done
as back as 2013 [2] :-\

-Emil
[1] https://github.com/Xilinx/linux-xlnx
[2] https://github.com/Xilinx/linux-xlnx/commit/aa76be1358005c42fadb2c7e9ac58a71a141dd7b