drm/i915: Mark the end of intel_ring_begin() and check in intel_ring_advance()

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It is required that the caller declare the exact number of dwords they
wish to write into the ring. This is required for two reasons, we need
to allocate sufficient space for the entire command packet and we need
to be sure that the contents are completely written to avoid executing
stale data. The current interface requires for any bug to be caught in
review, the reader has to carefully count the number of
intel_ring_emit() between intel_ring_begin() and intel_ring_advance().
If we record the end of the packet of each intel_ring_begin() we can
also have CI check for us.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170206170502.30944-1-chris@chris-wilson.co.uk

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This commit is contained in:

Chris Wilson 2017-02-06 17:05:01 +00:00

parent 04da811b3d

commit eca56a3511

3 changed files with 13 additions and 0 deletions

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9

drivers/gpu/drm/i915/i915_gem.h

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1

drivers/gpu/drm/i915/intel_ringbuffer.c

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3

drivers/gpu/drm/i915/intel_ringbuffer.h

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