[Intel-gfx] [PATCH 10/11] drm/i915/debugfs: add a separate debugfs file for VBT

[Chris Wilson]

On Mon, Dec 14, 2015 at 01:06:51PM +0200, Jani Nikula wrote:
> On Mon, 14 Dec 2015, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > On Mon, Dec 14, 2015 at 12:50:54PM +0200, Jani Nikula wrote:
> >> In the future the VBT might not be in mailbox #4 of the ACPI OpRegion,
> >> thus unavailable in i915_opregion, so add a separate file for the VBT.
> >> 
> >> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/i915_debugfs.c   | 22 ++++++++++++++++++++++
> >>  drivers/gpu/drm/i915/i915_drv.h       |  1 +
> >>  drivers/gpu/drm/i915/intel_opregion.c |  4 +++-
> >>  3 files changed, 26 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> >> index a9e1f18c36d1..aef1393e707f 100644
> >> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> >> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> >> @@ -1857,6 +1857,27 @@ out:
> >>  	return 0;
> >>  }
> >>  
> >> +static int i915_vbt(struct seq_file *m, void *unused)
> >> +{
> >> +	struct drm_info_node *node = m->private;
> >> +	struct drm_device *dev = node->minor->dev;
> >> +	struct drm_i915_private *dev_priv = dev->dev_private;
> >> +	struct intel_opregion *opregion = &dev_priv->opregion;
> >> +	int ret;
> >> +
> >> +	ret = mutex_lock_interruptible(&dev->struct_mutex);
> >
> > The contents of opregion->vbt are not serialised by struct_mutex, right?
> 
> Cargo culting ftw. I figured it was maybe for suspend/resume paths, but
> that doesn't really make sense does it?

No, the only thing that we control here are the dev_priv->opregion
pointers - and they are init only. So I think we are totally safe to
drop the struct_mutex.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre