[PATCH 15/16] drm/i915: Only one open() allowed on pipe CRC result files

Damien Lespiau
2013-10-15T17:56:04Z

It doesn't really make sense to have two processes dequeueing the CRC
values at the same time. Forbid that usage.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
---
drivers/gpu/drm/i915/i915_debugfs.c | 16 ++++++++++++++++
drivers/gpu/drm/i915/i915_drv.h | 1 +
2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 5137f8f..826ebce 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1768,6 +1768,15 @@ struct pipe_crc_info {

static int i915_pipe_crc_open(struct inode *inode, struct file *filep)
{
+ struct pipe_crc_info *info = inode->i_private;
+ struct drm_i915_private *dev_priv = info->dev->dev_private;
+ struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[info->pipe];
+
+ if (!atomic_dec_and_test(&pipe_crc->available)) {
+ atomic_inc(&pipe_crc->available);
+ return -EBUSY; /* already open */
+ }
+
filep->private_data = inode->i_private;

return 0;
@@ -1775,6 +1784,12 @@ static int i915_pipe_crc_open(struct inode *inode, struct file *filep)

static int i915_pipe_crc_release(struct inode *inode, struct file *filep)
{
+ struct pipe_crc_info *info = inode->i_private;
+ struct drm_i915_private *dev_priv = info->dev->dev_private;
+ struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[info->pipe];
+
+ atomic_inc(&pipe_crc->available); /* release the device */
+
return 0;
}

@@ -2684,6 +2699,7 @@ void intel_display_crc_init(struct drm_device *dev)
for (i = 0; i < INTEL_INFO(dev)->num_pipes; i++) {
struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[i];

+ atomic_set(&pipe_crc->available, 1);
init_waitqueue_head(&pipe_crc->wq);
}
}
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e16cf1e..3206358 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1234,6 +1234,7 @@ struct intel_pipe_crc_entry {

#define INTEL_PIPE_CRC_ENTRIES_NR 128
struct intel_pipe_crc {
+ atomic_t available; /* exclusive access to the device */
struct intel_pipe_crc_entry *entries;
enum intel_pipe_crc_source source;
atomic_t head, tail;
--
1.8.3.1