Re: [RESEND PATCH v3 05/11] drm: add Atmel HLCDC Display Controller support

[Boris BREZILLON <boris.brezillon@free-electrons.com>]

Hi Matt,

On Tue, 8 Jul 2014 16:51:24 -0700
Matt Roper <matthew.d.roper@intel.com> wrote:

> Hi Boris.
> 
> I haven't really looked at any of your driver in depth, but from a quick
> glance it looks like you're registering a cursor drm_plane (i.e., making
> use of the new universal plane infrastructure), but you're also
> providing an implementation of the legacy cursor ioctls (cursor_set and
> cursor_move).  There's some patches working their way through the
> pipeline that should make this unnecessary and hopefully simplify your
> life a bit:
> 
>         http://cgit.freedesktop.org/drm-intel/commit/?h=drm-intel-nightly&id=c394c2b08e247c32ef292b75fd8b34312465f8ae
>         http://cgit.freedesktop.org/drm-intel/commit/?h=drm-intel-nightly&id=b36552b32aa9c69e83a3a20bda56379fb9e52435
>         http://cgit.freedesktop.org/drm-intel/commit/?h=drm-intel-nightly&id=161d0dc1dccb17ff7a38f462c7c0d4ef8bcc5662
>         http://cgit.freedesktop.org/drm-intel/commit/?h=drm-intel-nightly&id=fc1d3e44ef7c1db93384150fdbf8948dcf949f15
> 
> The third patch there is the one that's really important for your work.
> When a driver provides a cursor plane via the universal plane interface,
> cursor_set and cursor_move are automatically implemented for you by
> drm_mode_cursor_universal() in drivers/gpu/drm/drm_crtc.c and your
> legacy handlers will never get called.  drm_mode_cursor_universal() will
> take care of wrapping the bo's into a drm_framebuffer for you.
> 
> When I added the universal cursor stuff, I wanted to make sure that as
> soon as a driver starts supporting universal planes it can stop
> supporting the legacy ioctls directly; otherwise handling refcounting
> when userspace switches back and forth between calling legacy ioctl's
> and calling setplane() on a cursor plane would be a nightmare.
> 
> I think those patches are only available in drm-intel-nightly at the
> moment and haven't moved on to drm-next and such yet, since i915 is the
> only driver that currently has patches to make use of cursors via the
> univeral plane interface (probably landing for kernel 3.17).

That's great news. I knew there were some work in progress on this
topic, but didn't know it was planned for 3.17. 

I'll move to this solution.

Thanks,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com