[Intel-gfx] [PATCH v6 22/24] drm/i915/dg1: DG1 does not support DC6

[Lucas De Marchi]

On Wed, Sep 30, 2020 at 09:50:07AM -0700, Matt Roper wrote:
>On Tue, Sep 29, 2020 at 11:42:32PM -0700, Lucas De Marchi wrote:
>> From: Anshuman Gupta <anshuman.gupta at intel.com>
>>
>> DC6 is not supported on DG1, so change the allowed DC mask for DG1.
>>
>> Cc: Uma Shankar <uma.shankar at intel.com>
>> Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
>
>Do we have a bspec reference for this?  I can't find anything specific
>about this from a casual skim of the pages I'd expect it to be mentioned
>on.
>
>If we have a reference added (or a note clarifying that we have offline
>confirmation from hardware architects),
>
>Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

I received confirmation from HW people that DG1 doesn't support DC6 and
spec is going to be updated.

Lucas De Marchi

>
>
>At some point I think we should re-write this section of the code in
>general.  The magic numbers used here are annoying, and a driver
>modparam named 'enable_dc' really sounds like it should be a bitmask of
>the exact DCs supported (rather than defining a combination of 'up to'
>values + DC3CO and omitting DC9 completely).  But we don't need to do
>that in a DG1 enabling patch.
>
>
>Matt
>
>> ---
>>  drivers/gpu/drm/i915/display/intel_display_power.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
>> index 0827e68a9d89..7dfc697ccf78 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
>> @@ -4689,7 +4689,10 @@ static u32 get_allowed_dc_mask(const struct drm_i915_private *dev_priv,
>>  	int max_dc;
>>
>>  	if (INTEL_GEN(dev_priv) >= 12) {
>> -		max_dc = 4;
>> +		if (IS_DG1(dev_priv))
>> +			max_dc = 3;
>> +		else
>> +			max_dc = 4;
>>  		/*
>>  		 * DC9 has a separate HW flow from the rest of the DC states,
>>  		 * not depending on the DMC firmware. It's needed by system
>> --
>> 2.28.0
>>
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>
>-- 
>Matt Roper
>Graphics Software Engineer
>VTT-OSGC Platform Enablement
>Intel Corporation
>(916) 356-2795