Re: [PATCH 1/2] drm/i915/chv: Add few more CHV workarounds

From: Jani Nikula <jani.nikula@linux.intel.com>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>,
	"Siluvery, Arun" <arun.siluvery@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/i915/chv: Add few more CHV workarounds
Date: Tue, 28 Oct 2014 17:02:14 +0200	[thread overview]
Message-ID: <8738a8kzk9.fsf@intel.com> (raw)
In-Reply-To: <20141028143926.GY4284@intel.com>

On Tue, 28 Oct 2014, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Tue, Oct 28, 2014 at 01:32:01PM +0000, Siluvery, Arun wrote:
>> On 28/10/2014 12:23, Ville Syrjälä wrote:
>> > On Tue, Oct 28, 2014 at 11:57:50AM +0000, Arun Siluvery wrote:
>> >> WaDisableInstructionShootdown:chv
>> >> WaForceEnableNonCoherent:chv
>> >> WaHdcDisableFetchWhenMasked:chv
>> >> WaDisableFenceDestinationToSLM:chv (pre-production)
>> >>
>> >> s/WaDisableDopClockGating/WaDisableRowChickenDopClockGating, because another
>> >> CHV WA is defined with the same name in intel_pm.c for a different reg.
>> >>
>> >> For: VIZ-4090
>> >> Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
>> >> ---
>> >>   drivers/gpu/drm/i915/i915_reg.h         |  2 ++
>> >>   drivers/gpu/drm/i915/intel_ringbuffer.c | 20 ++++++++++++++++++--
>> >>   2 files changed, 20 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>> >> index 77fce96..840e5d9 100644
>> >> --- a/drivers/gpu/drm/i915/i915_reg.h
>> >> +++ b/drivers/gpu/drm/i915/i915_reg.h
>> >> @@ -5024,6 +5024,7 @@ enum punit_power_well {
>> >>   /* GEN8 chicken */
>> >>   #define HDC_CHICKEN0				0x7300
>> >>   #define  HDC_FORCE_NON_COHERENT			(1<<4)
>> >> +#define  HDC_DONOT_FETCH_MEM_WHEN_MASKED	(1<<11)
>> >>   #define  HDC_FENCE_DEST_SLM_DISABLE		(1<<14)
>> >>
>> >>   /* WaCatErrorRejectionIssue */
>> >> @@ -5941,6 +5942,7 @@ enum punit_power_well {
>> >>   #define   GEN9_DG_MIRROR_FIX_ENABLE	(1<<5)
>> >>
>> >>   #define GEN8_ROW_CHICKEN		0xe4f0
>> >> +#define   INSTRUCTION_SHOOTDOWN_DISABLE (1<<9)
>> >>   #define   PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE	(1<<8)
>> >>   #define   STALL_DOP_GATING_DISABLE		(1<<5)
>> >>
>> >> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
>> >> index a8f72e8..2c07a02 100644
>> >> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
>> >> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
>> >> @@ -788,14 +788,30 @@ static int chv_init_workarounds(struct intel_engine_cs *ring)
>> >>   	struct drm_i915_private *dev_priv = dev->dev_private;
>> >>
>> >>   	/* WaDisablePartialInstShootdown:chv */
>> >> +	/* WaDisableInstructionShootdown:chv */
>> >>   	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
>> >> -		  PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);
>> >> +			  PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE |
>> >> +			  (dev->pdev->revision < 0x06 ?
>> >> +			   INSTRUCTION_SHOOTDOWN_DISABLE : 0));
>> >
>> > I think we should just drop the current early pre-prod workarounds, and
>> > not add more of them.
>> >
>> ok I will drop this.
>> Is there any guideline on particular revision for bdw, chv below which 
>> we should drop that workaround?
>
> The usual rule is to drop all pre-prod w/as once we know what actually
> is the first production stepping. But obviosuly it's still a bit too
> early to do that on chv. At this time I would just drop all A step ones.

Here's an idea.

Make all pre-prod workarounds conditional to i915.preliminary_hw_support.

Remove all pre-prod workarounds for a platform when that platform no
longer requires i915.preliminary_hw_support.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Technology Center
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