[Intel-gfx] [PATCH 2/4] drm/i915/tgl: Define MOCS entries for Tigerlake

[Daniele Ceraolo Spurio]

On 7/25/19 5:12 PM, 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.
> 
> v2: Add the missing entries in 49-51 range and replace "HW reserved"
>      terminology to what it actually is: L1 is implicitly enabled (from Daniele)
> 
> 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 | 37 +++++++++++++++++++++++++---
>   1 file changed, 34 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..ca370c7487f9 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), \


I've double-checked the specs and noticed that they now say that MOCS 0 
and 1 should be set to all zeros for Gen12 (possibly just to highlight 
the fact that they're deprecated/reserved). These are not supposes to be 
used so programming them to different values shouldn't matter, but it 
might be worth sticking to the specs and add a separate Gen12 table.

I've confirmed all the other entries in the gen11 table are kept the 
same in the TGL one, and the ones added below match the table as well.

> @@ -233,6 +240,30 @@ 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+: Implicitly enable L1 - HDC:L1 + L3 + LLC */ \
> +	MOCS_ENTRY(48, \
> +		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), \
> +		   L3_3_WB), \
> +	/* Gen12+: Implicitly enable L1 - HDC:L1 + L3 */ \
> +	MOCS_ENTRY(49, \
> +		   LE_1_UC | LE_TC_1_LLC, \
> +		   L3_3_WB), \
> +	/* Gen12+: Implicitly enable L1 - HDC:L1 + LLC */ \
> +	MOCS_ENTRY(50, \
> +		   LE_3_WB | LE_TC_1_LLC | LE_LRUM(3), \
> +		   L3_1_UC), \
> +	/* Gen12+: Implicitly enable L1 - HDC:L1 */ \
> +	MOCS_ENTRY(51, \
> +		   LE_1_UC | LE_TC_1_LLC, \
> +		   L3_1_UC), \
> +	/* Gen12+: HW Reserved - HW Special Case (CCS) */ \

Entries 60 and 61 are not reserved for HW usage but are special cases 
that trigger implicit behaviors. I'd drop the "HW Reserved" tag and 
leave just "HW Special Case"

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), \
>