Well, as well as we can without completely revamping the drm vblank
code. The issue are that
- The vblank code needs to work on both ums and kms.
- It deals always deals with pipes.
- It doesn't take any of the kms locks.
The last part is not really fixable without revamping the drm vblank
code, since the drm core <-> driver interactions is a veritable pile
of spaghettis. But the other pieces can be fixed by switching on the
MODESET driver flag and either checking the hw state directly (ums
case) or just querying our sw tracking (with broken locking, but
that's not worse than what we've had).
Note that this essentially reverts
commit 702e7a56af
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date: Tue Oct 23 18:29:59 2012 -0200
drm/i915: convert PIPECONF to use transcoder instead of pipe
for the ums case, which will fix a NULL deref (since we really don't
have any crtcs set up).
But the real reason to do this is to drop our reliance on the
cpu_transcoder: By only checking intel_crtc->active we don't need to
make sure that the pipe_config (or at least the cpu_transcoder)
contain safe values even when the pipe is off.
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
************************************************************
* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
************************************************************
The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html
a01025afa8