In DRM/KMS we are lacking a good way to deal with tiled/compressed
formats. Especially in the case of dmabuf/prime buffer sharing, where
we cannot always rely on under-the-hood flags passed to driver specific
gem-create ioctl to pass around these extra flags.
The proposal is to add a per-plane format modifier. This allows to, if
necessary, use different tiling patters for sub-sampled planes, etc.
The format modifiers are added at the end of the ioctl struct, so for
legacy userspace it will be zero padded.
v1: original
v1.5: increase modifier to 64b
v2: Incorporate review comments from the big thread, plus a few more.
- Add a getcap so that userspace doesn't have to jump through hoops.
- Allow modifiers only when a flag is set. That way drivers know when
they're dealing with old userspace and need to fish out e.g. tiling
from other information.
- After rolling out checks for ->modifier to all drivers I've decided
that this is way too fragile and needs an explicit opt-in flag. So
do that instead.
- Add a define (just for documentation really) for the "NONE"
modifier. Imo we don't need to add mask #defines since drivers
really should only do exact matches against values defined with
fourcc_mod_code.
- Drop the Samsung tiling modifier on Rob's request since he's not yet
sure whether that one is accurate.
v3:
- Also add a new ->modifier[] array to struct drm_framebuffer and fill
it in drm_helper_mode_fill_fb_struct. Requested by Tvrkto Uruslin.
- Remove TODO in comment and add code comment that modifiers should be
properly documented, requested by Rob.
Cc: Rob Clark <robdclark@gmail.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Daniel Stone <daniel@fooishbar.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Rob Clark <robdclark@gmail.com> (v1.5)
Reviewed-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
So this has been merged originally in
commit 83052d4d5c
Author: Seung-Woo Kim <sw0312.kim@samsung.com>
Date: Thu Dec 15 15:40:55 2011 +0900
drm: Add multi buffer plane pixel formats
which hasn't seen a lot of review really. The problem is that it's not
a real pixel format, but just a different way to lay out NV12 pixels
in macroblocks, i.e. a tiling format.
The new way of doing this is with the soon-to-be-merged fb modifiers.
This was brough up in some long irc discussion around the entire
topic, as an example of where things have gone wrong. Luckily we can
correct the mistake:
- The kms side support for NV12MT is all dead code because
format_check in drm_crtc.c never accepted NV12MT.
- The gem side for the gsc support doesn't look better: The code
forgets to set the pixel format and makes a big mess with the tiling
mode bits, inadvertedly setting them all.
Conclusion: This never really worked (at least not in upstream) and
hence we can safely correct our mistake here.
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Rob Clark <robclark@freedesktop.org>
Cc: Daniel Stone <daniel@fooishbar.org>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Rob Clark <robclark@freedesktop.org>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Acked-by: Joonyoung Shim <jy0922.shim@samsung.com>
Acked-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Rob Clark