[Intel-gfx] [PATCH 18/22] drm/i915/tgl: Define MOCS entries for Tigerlake

[Daniele Ceraolo Spurio]

On 7/18/19 6:08 AM, Ville Syrjälä wrote:
> On Fri, Jul 12, 2019 at 06:09:36PM -0700, Lucas De Marchi wrote:
>> From: Tomasz Lis <tomasz.lis at intel.com>
>>
>> The MOCS table is published as part of bspec, and versioned. Entries
>> are supposed to never be modified, but new ones can be added. Adding
>> entries increases table version. The patch includes version 1 entries.
>>
>> Two of the 3 legacy entries used for gen9 are no longer expected to work.
>> Although we are changing the gen11 table, those changes are supposed to
>> be backward compatible since we are only touching previously undefined
>> entries.
>>
>> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
>> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
>> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>> Signed-off-by: Tomasz Lis <tomasz.lis at intel.com>
>> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_mocs.c | 25 ++++++++++++++++++++++---
>>   1 file changed, 22 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_mocs.c b/drivers/gpu/drm/i915/gt/intel_mocs.c
>> index 290a5e9b90b9..259e7bec0a63 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_mocs.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_mocs.c
>> @@ -62,6 +62,10 @@ struct drm_i915_mocs_table {
>>   #define GEN11_NUM_MOCS_ENTRIES	64  /* 63-64 are reserved, but configured. */
>>   
>>   /* (e)LLC caching options */
>> +/*
>> + * Note: LE_0_PAGETABLE works only up to Gen11; for newer gens it means
>> + * the same as LE_UC
>> + */
>>   #define LE_0_PAGETABLE		_LE_CACHEABILITY(0)
>>   #define LE_1_UC			_LE_CACHEABILITY(1)
>>   #define LE_2_WT			_LE_CACHEABILITY(2)
>> @@ -100,8 +104,9 @@ struct drm_i915_mocs_table {
>>    * of bspec.
>>    *
>>    * Entries not part of the following tables are undefined as far as
>> - * userspace is concerned and shouldn't be relied upon.  For the time
>> - * being they will be initialized to PTE.
>> + * userspace is concerned and shouldn't be relied upon.  For Gen < 12
>> + * they will be initialized to PTE. Gen >= 12 onwards don't have a setting for
>> + * PTE. We use the same value, but that actually means Uncached.
>>    *
>>    * The last two entries are reserved by the hardware. For ICL+ they
>>    * should be initialized according to bspec and never used, for older
>> @@ -137,11 +142,13 @@ static const struct drm_i915_mocs_entry broxton_mocs_table[] = {
>>   };
>>   
>>   #define GEN11_MOCS_ENTRIES \
>> -	/* Base - Uncached (Deprecated) */ \
>> +	/* Gen11: Base - Uncached (Deprecated) */ \
>> +	/* Gen12+: Base - Error (Reserved for Non-Use) */ \
>>   	MOCS_ENTRY(I915_MOCS_UNCACHED, \
>>   		   LE_1_UC | LE_TC_1_LLC, \
>>   		   L3_1_UC), \
>>   	/* Base - L3 + LeCC:PAT (Deprecated) */ \
>> +	/* Gen12+: Base - Reserved */ \
>>   	MOCS_ENTRY(I915_MOCS_PTE, \
>>   		   LE_0_PAGETABLE | LE_TC_1_LLC, \
>>   		   L3_3_WB), \
>> @@ -233,6 +240,18 @@ static const struct drm_i915_mocs_entry broxton_mocs_table[] = {
>>   	MOCS_ENTRY(23, \
>>   		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3) | LE_RSC(1) | LE_SCC(7), \
>>   		   L3_3_WB), \
>> +	/* Gen12+: HW Reserved - HDC:L1 + L3 + LLC */ \
> 
> Why is this marked as reserved? From the looks of things 48-61 should
> just be normal entries that userspace can select to get HDC L1$. And
> looks like icl already has that stuff. So someone should probably figure
> out if Mesa/etc. can make use of the HDC L1$, and if so we should add
> the relevant MOCS entries for icl as well.

Here the reserved terminology is indeed misleading. The 48-59 range is a 
"special" range where L1 usage is implicitly enabled by the HW, as there 
is no explicit L1 toggle in the MOCS registers. The reserved here means 
that the range shouldn't be used for "normal" MOCS settings, but SW can 
freely use these entries as needed. Similarly, MOCS 60 and 61 are 
reserved for other special purposes, but are still usable by SW. The 
only entries SW shouldn't touch are 62 and 63.

Regarding ICL, Gen11 HW doesn't have the capability so no new entries 
are required there.

> 
>> +	MOCS_ENTRY(48, \
>> +		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), \
>> +		   L3_3_WB), \
>> +	/* Gen12+: HW Reserved - HW Special Case (CCS) */ \

The specs have MOCS 49-51 defined as well.

Daniele

>> +	MOCS_ENTRY(60, \
>> +		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), \
>> +		   L3_1_UC), \
>> +	/* Gen12+: HW Reserved - HW Special Case (Displayable) */ \
>> +	MOCS_ENTRY(61, \
>> +		   LE_1_UC | LE_TC_1_LLC | LE_SCF(1), \
>> +		   L3_3_WB), \
>>   	/* HW Reserved - SW program but never use */ \
>>   	MOCS_ENTRY(62, \
>>   		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), \
>> -- 
>> 2.21.0
>