[Intel-gfx] [PATCH] drm/i915: remove check for aux irq

[Lucas De Marchi]

On Thu, Apr 26, 2018 at 06:50:05PM +0300, Ville Syrjälä wrote:
> On Thu, Apr 26, 2018 at 08:42:54AM -0700, Lucas De Marchi wrote:
> > On Thu, Apr 26, 2018 at 06:27:26PM +0300, Ville Syrjälä wrote:
> > > On Thu, Apr 26, 2018 at 08:22:12AM -0700, Lucas De Marchi wrote:
> > > > On Thu, Apr 26, 2018 at 04:43:38PM +0300, Ville Syrjälä wrote:
> > > > > On Wed, Apr 25, 2018 at 02:55:24PM -0700, Lucas De Marchi wrote:
> > > > > > This became dead code with commit 309bd8ed464f ("drm/i915: Reinstate
> > > > > > GMBUS and AUX interrupts on gen4/g4x").
> > > > > > 
> > > > > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > > > Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> > > > > > ---
> > > > > >  drivers/gpu/drm/i915/i915_drv.h  |  3 +--
> > > > > >  drivers/gpu/drm/i915/intel_dp.c  | 22 +++++++---------------
> > > > > >  drivers/gpu/drm/i915/intel_drv.h |  1 -
> > > > > >  drivers/gpu/drm/i915/intel_psr.c |  2 +-
> > > > > >  4 files changed, 9 insertions(+), 19 deletions(-)
> > > > > > 
> > > > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > > > > > index 8444ca8d5aa3..09e1c2289ea1 100644
> > > > > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > > > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > > > > @@ -2545,7 +2545,7 @@ intel_info(const struct drm_i915_private *dev_priv)
> > > > > >  	 IS_SKL_GT3(dev_priv) || IS_SKL_GT4(dev_priv))
> > > > > >  
> > > > > >  /*
> > > > > > - * dp aux and gmbus irq on gen4 seems to be able to generate legacy interrupts
> > > > > > + * gmbus irq on gen4 seems to be able to generate legacy interrupts
> > > > > 
> > > > > Why are you removing vital information from the comment?
> > > > 
> > > > Because it wouldn't match the code anymore. We always use aux irq.
> > > 
> > > The comment is documenting the hardware behaviour. We don't want to lose
> > > that information.
> > 
> > IMO it's confusing to have the comment saying one thing and then code
> > not following it. Reading it again I see the second paragraph you added
> > actually document the code and the first the HW behavior. Maybe starting
> > the second paragraph with a "However" would make it clearer.  Or I can just
> > drop this change in the comment.
> 
> Or you can move the relevant parts of the comment to the place where
> we do the "MSI or not to MSI" decision.

Humn, not sure I fully understand what you mean by relevant part. Do you
mean something like this?

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index b7dbeba72dec..3fc6b915dac1 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1183,6 +1183,9 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 	 * get lost on g4x as well, and interrupt delivery seems to stay
 	 * properly dead afterwards. So we'll just disable them for all
 	 * pre-gen5 chipsets.
+	 *
+	 * Since we don't enable MSI on gen <= 4 we can always use GMBUS/AUX
+	 * interrupts.
 	 */
 	if (INTEL_GEN(dev_priv) >= 5) {
 		if (pci_enable_msi(pdev) < 0)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 09e1c2289ea1..5fd47227da23 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2545,13 +2545,10 @@ intel_info(const struct drm_i915_private *dev_priv)
 	 IS_SKL_GT3(dev_priv) || IS_SKL_GT4(dev_priv))
 
 /*
- * gmbus irq on gen4 seems to be able to generate legacy interrupts
+ * dp aux and gmbus irq on gen4 seems to be able to generate legacy interrupts
  * even when in MSI mode. This results in spurious interrupt warnings if the
  * legacy irq no. is shared with another device. The kernel then disables that
  * interrupt source and so prevents the other device from working properly.
- *
- * Since we don't enable MSI anymore on gen4, we can always use GMBUS/AUX
- * interrupts.
  */
 #define HAS_GMBUS_IRQ(dev_priv) (INTEL_GEN(dev_priv) >= 4)
 
-------

It doesn't seem clearer to me.

Lucas De Marchi


> 
> -- 
> Ville Syrjälä
> Intel