[PATCH] drm/i915: Stop CRC gathering when the ctl file is closed

[PATCH] drm/i915: Stop CRC gathering when the ctl file is closed

[ville.syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

If no one is looking at the CRCs, stop gathering them.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index eb61c4b..e7470b8 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2294,12 +2294,25 @@ out:
 	return len;
 }
 
+static int display_crc_ctl_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = file->private_data;
+	struct drm_device *dev = m->private;
+	enum pipe pipe;
+
+	/* stop gathering CRCs */
+	for_each_pipe(pipe)
+		pipe_crc_set_source(dev, pipe, INTEL_PIPE_CRC_SOURCE_NONE);
+
+	return single_release(inode, file);
+}
+
 static const struct file_operations i915_display_crc_ctl_fops = {
 	.owner = THIS_MODULE,
 	.open = display_crc_ctl_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
-	.release = single_release,
+	.release = display_crc_ctl_release,
 	.write = display_crc_ctl_write
 };
 
-- 
1.8.1.5

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Re: [PATCH] drm/i915: Stop CRC gathering when the ctl file is closed

[Daniel Vetter]

On Mon, Oct 21, 2013 at 6:01 PM,  <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> If no one is looking at the CRCs, stop gathering them.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

As discussed on irc this prevents fools like me from wreaking havoc
directly with the cli, at least if you still want to interactively
test stuff easily (background processes and all would work around
this). Imo it's better to disable (and maybe re-enable) the CRC stuff
when we disable/enable the pipe.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

Re: [PATCH] drm/i915: Stop CRC gathering when the ctl file is closed

[Ville Syrjälä]

On Mon, Oct 21, 2013 at 06:17:30PM +0200, Daniel Vetter wrote:
> On Mon, Oct 21, 2013 at 6:01 PM,  <ville.syrjala@linux.intel.com> wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > If no one is looking at the CRCs, stop gathering them.
> >
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> As discussed on irc this prevents fools like me from wreaking havoc
> directly with the cli, at least if you still want to interactively
> test stuff easily (background processes and all would work around
> this). Imo it's better to disable (and maybe re-enable) the CRC stuff
> when we disable/enable the pipe.

I would still suggest using exec for keeping the file open.

Especially if we go for the auto re-enable, since then we'd
essientially never turn off the crc capture once it's started
unless someone explicitly writes to the ctl file. We'd just pause
it while the pipe is off.

Also I would assume we want to avoid full modesets in the future
if possible, so relying on that doesn't feel very robust to me.

-- 
Ville Syrjälä
Intel OTC