[Intel-gfx] [PATCH 1/3] drm/i915: add PCH_NONE to enum intel_pch

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

And rely on the fact that it's 0 to assume that machines without a PCH
will have PCH_NONE as dev_priv->pch_type.

Just today I finally realized that HAS_PCH_IBX is true for machines
without a PCH. IMHO this is totally counter-intuitive and I don't
think it's a good idea to assume that we're going to check for
HAS_PCH_IBX only after we check for HAS_PCH_SPLIT.

I believe that in the future we'll have more PCH types and checks
like:

    if (HAS_PCH_IBX(dev) || HAS_PCH_CPT(dev))

will become more and more common. There's a good chance that we may
break non-PCH machines by adding these checks in code that runs on all
machines. I also believe that the HAS_PCH_SPLIT check will become less
common as we add more and more different PCH types.

Also: are we sure we don't already have any bugs triggered by checking
for HAS_PCH_IBX on non-PCH machines?

Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |    1 +
 1 file changed, 1 insertion(+)

Another alternative would have been to change HAS_PCH_IBX to also
check for HAS_PCH_SPLIT, but I'm not exactly in favor of adding more
conditionals...

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b7a1eaa..b12e79a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -333,6 +333,7 @@ enum no_fbc_reason {
 };
 
 enum intel_pch {
+	PCH_NONE = 0,	/* No PCH present */
 	PCH_IBX,	/* Ibexpeak PCH */
 	PCH_CPT,	/* Cougarpoint PCH */
 	PCH_LPT,	/* Lynxpoint PCH */
-- 
1.7.10.2