drm/i915: Empty the circular buffer when asked for a new source

So we don't read out stale CRCs from a previous run left in the buffer.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 787c50d..ec9151a 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1820,6 +1820,12 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe,
        if (pipe_crc->source && source)
                return -EINVAL;
 
+       /* none -> real source transition */
+       if (source) {
+               atomic_set(&pipe_crc->head, 0);
+               atomic_set(&pipe_crc->tail, 0);
+       }
+
        pipe_crc->source = source;
 
        switch (source) {