One more attempt at making FBC suck a bit less.
The main thing as before is getting the LRI based render/blitter
tracking in place.
In this updates series I decided the way to avoid the kms locks in
execbuffer is to keep an extra reference to the fb.
I added a bunch of locking (struct_mutex and crtc->mutex) to some
places to hopefully make it bit less racy. I think/hope that it doesn't
make it more likely to deadlock. We do grab both locks in the fbc work
now, and we do cancel the work while holding at least one of the locks,
so it seems a bit bad. But we cancel the work in a lazy fashion (no _sync
or anything) so I don't think it should deadlock due to that. And we
already grabbed struct_mutex there anyway, and we already held it while
cancelling the work, so it's no worse at least :P
The disable_fbc/update_fbc calls from the page flip code are lacking
kms lock protection, but we can't simply add it there due to possibility
of deadlocks.
So at least the render/blitter tracking seems to work now without
upsetting lockdep, so it seems a bit better than what we had at least.
Maybe someone else will get inspired by this and fix this mess up for
real...
I've only run this on my IVB, and just running X + some apps w/o
a compositor. No extensive tests or anything. But if I frob some
debug register to disable some tracking bits the screen gets
corrupted, so it seems to be doing its job.
I pushed it here in case someone is interested in a git tree:
git://gitorious.org/vsyrjala/linux.git fbc_fixes
Ville Syrjälä (10):
drm/i915: Use plane_name() in gen7_enable_fbc()
drm/i915: Grab struct_mutex around all FBC updates
drm/i915: Have FBC keep references to the fb
drm/i915: Grab crtc->mutex in intel_fbc_work_fn()
drm/i915: Limit FBC flush to post batch flush
drm/i915: Emit SRM after the MSG_FBC_REND_STATE LRI
drm/i915: Implement LRI based FBC tracking
drm/i915: Kill sandybridge_blit_fbc_update()
drm/i915: Don't write ILK/IVB_FBC_RT_BASE directly
drm/i915: Set has_fbc=true for all SNB+, except VLV
drivers/gpu/drm/i915/i915_drv.c | 6 +-
drivers/gpu/drm/i915/i915_drv.h | 6 +-
drivers/gpu/drm/i915/i915_gem_context.c | 7 +++
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 31 ++++++++++
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_display.c | 27 +++++++-
drivers/gpu/drm/i915/intel_drv.h | 1 +
drivers/gpu/drm/i915/intel_pm.c | 98 ++++++++++++++++--------------
drivers/gpu/drm/i915/intel_ringbuffer.c | 66 ++++++++++++++++++--
drivers/gpu/drm/i915/intel_ringbuffer.h | 2 +
10 files changed, 188 insertions(+), 57 deletions(-)
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