Re: [PATCH] drm/i915: Check for fused or unused pipes

[Mika Kahola <mika.kahola@intel.com>]

On Fri, 2017-12-15 at 11:27 +0200, Jani Nikula wrote:
> On Fri, 15 Dec 2017, Dhinakaran Pandiyan <dhinakaran.pandiyan@gmail.c
> om> wrote:
> > 
> > On Friday, December 15, 2017 9:59:02 AM PST Mika Kahola wrote:
> > > 
> > > In case of fused or unused pipes, return early with a warning
> > > when reading
> > > information for encoder.
> > > 
> > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103206
> > > Reported-by: Thomas Gleixner <tglx@linutronix.de>
> > > Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> > > Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_audio.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_audio.c
> > > b/drivers/gpu/drm/i915/intel_audio.c index f1502a0..522d54f
> > > 100644
> > > --- a/drivers/gpu/drm/i915/intel_audio.c
> > > +++ b/drivers/gpu/drm/i915/intel_audio.c
> > > @@ -779,7 +779,7 @@ static struct intel_encoder
> > > *get_saved_enc(struct
> > > drm_i915_private *dev_priv, {
> > >  	struct intel_encoder *encoder;
> > > 
> > > -	if (WARN_ON(pipe >= INTEL_INFO(dev_priv)->num_pipes))
> > > +	if (WARN_ON(pipe >= ARRAY_SIZE(dev_priv->av_enc_map)))
> > >  		return NULL;
> > I think we should remove the WARN_ON() and just return NULL. The
> > error return 
> > and the debug message we print in the caller is good enough IMO. 
> On the contrary, I think this one is fine with WARN_ON. The commit
> message is inaccurate. This will only become a bounds check with the
> change, and I think it's important to catch the totally out of bounds
> values loudly.
Well, I need to rephrase that commit message. 
> 
> In case of fused or unused pipes, the code will happily pass that
> check,
> and check the av_enc_map for whether the pipe is available or not.
> 
> BR,
> Jani.
> 
> 
> > 
> > 
> > > 
> > > 
> > >  	/* MST */
> > 
-- 
Mika Kahola - Intel OTC

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