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Commit 5dd8e50c authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Replace manual barrier() with READ_ONCE() in HWS accessor 



When reading from the HWS page, we use barrier() to prevent the compiler
optimising away the read from the volatile (may be updated by the GPU)
memory address. This is more suited to READ_ONCE(); make it so.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460195877-20520-5-git-send-email-chris@chris-wilson.co.uk
parent 0d317ce9

drivers/gpu/drm/i915/intel_ringbuffer.h

+2 −4
Original line number Diff line number Diff line
@@ -391,12 +391,10 @@ intel_flush_status_page(struct intel_engine_cs *engine, int reg) 
}



static inline u32

intel_read_status_page(struct intel_engine_cs *engine,

		       int reg)

intel_read_status_page(struct intel_engine_cs *engine, int reg)

{

	/* Ensure that the compiler doesn't optimize away the load. */

	barrier();

	return engine->status_page.page_addr[reg];

	return READ_ONCE(engine->status_page.page_addr[reg]);

}



static inline void