Re: [PATCH 2/3] drm/i915: Promote IS_BROADWELL to a simple macro

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 2/3] drm/i915: Promote IS_BROADWELL to a simple macro
Date: Fri, 6 May 2016 17:29:18 +0300	[thread overview]
Message-ID: <20160506142918.GD4329@intel.com> (raw)
In-Reply-To: <572CA7A8.7010806@linux.intel.com>

On Fri, May 06, 2016 at 03:18:16PM +0100, Tvrtko Ursulin wrote:
> 
> On 06/05/16 15:00, Ville Syrjälä wrote:
> > On Fri, May 06, 2016 at 02:43:50PM +0100, Tvrtko Ursulin wrote:
> >> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> >>
> >> If we allow it a dedicated flag in dev_priv we enable the
> >> compiler to nicely optimize conditions like IS_HASSWELL ||
> >> IS_BROADWELL.
> >>
> >> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> >> ---
> >>   drivers/gpu/drm/i915/i915_drv.c | 4 ++++
> >>   drivers/gpu/drm/i915/i915_drv.h | 3 ++-
> >>   2 files changed, 6 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> >> index 9fd221c97275..da6532da44e3 100644
> >> --- a/drivers/gpu/drm/i915/i915_drv.c
> >> +++ b/drivers/gpu/drm/i915/i915_drv.c
> >> @@ -300,22 +300,26 @@ static const struct intel_device_info intel_haswell_m_info = {
> >>   static const struct intel_device_info intel_broadwell_d_info = {
> >>   	BDW_FEATURES,
> >>   	.gen = 8,
> >> +	.is_broadwell = 1,
> >>   };
> >>
> >>   static const struct intel_device_info intel_broadwell_m_info = {
> >>   	BDW_FEATURES,
> >>   	.gen = 8, .is_mobile = 1,
> >> +	.is_broadwell = 1,
> >>   };
> >>
> >>   static const struct intel_device_info intel_broadwell_gt3d_info = {
> >>   	BDW_FEATURES,
> >>   	.gen = 8,
> >> +	.is_broadwell = 1,
> >>   	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING | BSD2_RING,
> >>   };
> >>
> >>   static const struct intel_device_info intel_broadwell_gt3m_info = {
> >>   	BDW_FEATURES,
> >>   	.gen = 8, .is_mobile = 1,
> >> +	.is_broadwell = 1,
> >>   	.ring_mask = RENDER_RING | BSD_RING | BLT_RING | VEBOX_RING | BSD2_RING,
> >>   };
> >>
> >> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> >> index c6351016eaf0..459561991081 100644
> >> --- a/drivers/gpu/drm/i915/i915_drv.h
> >> +++ b/drivers/gpu/drm/i915/i915_drv.h
> >> @@ -735,6 +735,7 @@ struct intel_csr {
> >>   	func(is_valleyview) sep \
> >>   	func(is_cherryview) sep \
> >>   	func(is_haswell) sep \
> >> +	func(is_broadwell) sep \
> >>   	func(is_skylake) sep \
> >>   	func(is_broxton) sep \
> >>   	func(is_kabylake) sep \
> >
> > We could just replace all of these with a single enum and save a bunch
> > of space.
> 
> Bitfield is really nice here because compiler can then merge tests like 
> IS_HASWELL || IS_BROADWELL into a single test instruction.

Most if not all of those are in modeset code so I'm not entirely
convinced micro-optimizing that is all that useful.

Bunch of times I've just wished I could write 'whatever >= G4X' instead
of 'IS_G4X || gen >= 5' simply for readability.

> 
> Regards,
> 
> Tvrtko
> 
> >
> >> @@ -2553,7 +2554,7 @@ struct drm_i915_cmd_table {
> >>   #define IS_VALLEYVIEW(dev)	(INTEL_INFO(dev)->is_valleyview)
> >>   #define IS_CHERRYVIEW(dev)	(INTEL_INFO(dev)->is_cherryview)
> >>   #define IS_HASWELL(dev)	(INTEL_INFO(dev)->is_haswell)
> >> -#define IS_BROADWELL(dev)	(!INTEL_INFO(dev)->is_cherryview && IS_GEN8(dev))
> >> +#define IS_BROADWELL(dev)	(INTEL_INFO(dev)->is_broadwell)
> >>   #define IS_SKYLAKE(dev)	(INTEL_INFO(dev)->is_skylake)
> >>   #define IS_BROXTON(dev)		(INTEL_INFO(dev)->is_broxton)
> >>   #define IS_KABYLAKE(dev)	(INTEL_INFO(dev)->is_kabylake)
> >> --
> >> 1.9.1
> >>
> >> _______________________________________________
> >> Intel-gfx mailing list
> >> Intel-gfx@lists.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >

-- 
Ville Syrjälä
Intel OTC
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