drm/i915: Use a spin lock to protect the pipe crc struct
authorDamien Lespiau <damien.lespiau@intel.com>
Mon, 21 Oct 2013 13:29:30 +0000 (14:29 +0100)
committerDaniel Vetter <daniel.vetter@ffwll.ch>
Mon, 21 Oct 2013 22:27:49 +0000 (00:27 +0200)
commitd538bbdfde34028b5c5b0ba92b3c2096c5afb82c
tree20bd5f906e81cf13ae577048608d8f77be8f72b4
parentc459787294e8375210a3d26fe8ed83f40eca3276
drm/i915: Use a spin lock to protect the pipe crc struct

Daniel pointed out that it was hard to get anything lockless to work
correctly, so don't even try for this non critical piece of code and
just use a spin lock.

v2: Make intel_pipe_crc->opened a bool
v3: Use assert_spin_locked() instead of a comment (Daniel Vetter)
v4: Use spin_lock_irq() in the debugfs functions (they can only be
    called from process context),
    Use spin_lock() in the pipe_crc_update() function that can only be
    called from an interrupt handler,
    Use wait_event_interruptible_lock_irq() when waiting for data in the
    cicular buffer to ensure proper locking around the condition we are
    waiting for. (Daniel Vetter)

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
drivers/gpu/drm/i915/i915_debugfs.c
drivers/gpu/drm/i915/i915_drv.h
drivers/gpu/drm/i915/i915_irq.c