Re: [PATCH v8 6/7] drm/i915: cache number of MOCS entries

["Lis, Tomasz" <tomasz.lis@xxxxxxxxx>]

On 2019-01-22 06:12, Lucas De Marchi wrote:
> Instead of checking the gen number every time we need to know the max
> number of entries, just save it into the table struct so we don't need
> extra branches throughout the code. This will be useful for Ice Lake
> that has 64 rather than 62 defined entries. Ice Lake changes will be
> added in a follow up.
>
> v2: make size and n_entries `unsigned int` and introduce changes as a
>      pre-work for the Ice Lake changes (Tvrtko)
>
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
I would name it total_entries or n_hw_entries, not n_entries; but that's 
just a name, so:
Reviewed-by: Tomasz Lis <tomasz.lis@xxxxxxxxx>
-Tomasz
> ---
>   drivers/gpu/drm/i915/intel_mocs.c | 27 ++++++++++++++-------------
>   1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_mocs.c b/drivers/gpu/drm/i915/intel_mocs.c
> index af2ae2f396ae..716f3f6f2966 100644
> --- a/drivers/gpu/drm/i915/intel_mocs.c
> +++ b/drivers/gpu/drm/i915/intel_mocs.c
> @@ -32,7 +32,8 @@ struct drm_i915_mocs_entry {
>   };
>   
>   struct drm_i915_mocs_table {
> -	u32 size;
> +	unsigned int size;
> +	unsigned int n_entries;
>   	const struct drm_i915_mocs_entry *table;
>   };
>   
> @@ -140,10 +141,12 @@ static bool get_mocs_settings(struct drm_i915_private *dev_priv,
>   	if (IS_GEN9_BC(dev_priv) || IS_CANNONLAKE(dev_priv) ||
>   	    IS_ICELAKE(dev_priv)) {
>   		table->size  = ARRAY_SIZE(skylake_mocs_table);
> +		table->n_entries = GEN9_NUM_MOCS_ENTRIES;
>   		table->table = skylake_mocs_table;
>   		result = true;
>   	} else if (IS_GEN9_LP(dev_priv)) {
>   		table->size  = ARRAY_SIZE(broxton_mocs_table);
> +		table->n_entries = GEN9_NUM_MOCS_ENTRIES;
>   		table->table = broxton_mocs_table;
>   		result = true;
>   	} else {
> @@ -202,8 +205,6 @@ void intel_mocs_init_engine(struct intel_engine_cs *engine)
>   	if (!get_mocs_settings(dev_priv, &table))
>   		return;
>   
> -	GEM_BUG_ON(table.size > GEN9_NUM_MOCS_ENTRIES);
> -
>   	/* Set unused values to PTE */
>   	unused_value = table.table[I915_MOCS_PTE].control_value;
>   
> @@ -215,7 +216,7 @@ void intel_mocs_init_engine(struct intel_engine_cs *engine)
>   	}
>   
>   	/* All remaining entries are also unused */
> -	for (; index < GEN9_NUM_MOCS_ENTRIES; index++)
> +	for (; index < table.n_entries; index++)
>   		I915_WRITE(mocs_register(engine->id, index), unused_value);
>   }
>   
> @@ -237,17 +238,17 @@ static int emit_mocs_control_table(struct i915_request *rq,
>   	u32 unused_value;
>   	u32 *cs;
>   
> -	if (WARN_ON(table->size > GEN9_NUM_MOCS_ENTRIES))
> +	if (GEM_WARN_ON(table->size > table->n_entries))
>   		return -ENODEV;
>   
>   	/* Set unused values to PTE */
>   	unused_value = table->table[I915_MOCS_PTE].control_value;
>   
> -	cs = intel_ring_begin(rq, 2 + 2 * GEN9_NUM_MOCS_ENTRIES);
> +	cs = intel_ring_begin(rq, 2 + 2 * table->n_entries);
>   	if (IS_ERR(cs))
>   		return PTR_ERR(cs);
>   
> -	*cs++ = MI_LOAD_REGISTER_IMM(GEN9_NUM_MOCS_ENTRIES);
> +	*cs++ = MI_LOAD_REGISTER_IMM(table->n_entries);
>   
>   	for (index = 0; index < table->size; index++) {
>   		u32 value = table->table[index].used ?
> @@ -258,7 +259,7 @@ static int emit_mocs_control_table(struct i915_request *rq,
>   	}
>   
>   	/* All remaining entries are also unused */
> -	for (; index < GEN9_NUM_MOCS_ENTRIES; index++) {
> +	for (; index < table->n_entries; index++) {
>   		*cs++ = i915_mmio_reg_offset(mocs_register(engine, index));
>   		*cs++ = unused_value;
>   	}
> @@ -294,17 +295,17 @@ static int emit_mocs_l3cc_table(struct i915_request *rq,
>   	unsigned int i, unused_index;
>   	u32 *cs;
>   
> -	if (WARN_ON(table->size > GEN9_NUM_MOCS_ENTRIES))
> +	if (GEM_WARN_ON(table->size > table->n_entries))
>   		return -ENODEV;
>   
>   	/* Set unused values to PTE */
>   	unused_index = I915_MOCS_PTE;
>   
> -	cs = intel_ring_begin(rq, 2 + GEN9_NUM_MOCS_ENTRIES);
> +	cs = intel_ring_begin(rq, 2 + table->n_entries);
>   	if (IS_ERR(cs))
>   		return PTR_ERR(cs);
>   
> -	*cs++ = MI_LOAD_REGISTER_IMM(GEN9_NUM_MOCS_ENTRIES / 2);
> +	*cs++ = MI_LOAD_REGISTER_IMM(table->n_entries / 2);
>   
>   	for (i = 0; i < table->size / 2; i++) {
>   		u16 low = table->table[2 * i].used ?
> @@ -327,7 +328,7 @@ static int emit_mocs_l3cc_table(struct i915_request *rq,
>   	}
>   
>   	/* All remaining entries are also unused */
> -	for (; i < GEN9_NUM_MOCS_ENTRIES / 2; i++) {
> +	for (; i < table->n_entries / 2; i++) {
>   		*cs++ = i915_mmio_reg_offset(GEN9_LNCFCMOCS(i));
>   		*cs++ = l3cc_combine(table, unused_index, unused_index);
>   	}
> @@ -384,7 +385,7 @@ void intel_mocs_init_l3cc_table(struct drm_i915_private *dev_priv)
>   	}
>   
>   	/* Now set the rest of the table to PTE */
> -	for (; i < (GEN9_NUM_MOCS_ENTRIES / 2); i++)
> +	for (; i < table.n_entries / 2; i++)
>   		I915_WRITE(GEN9_LNCFCMOCS(i),
>   			   l3cc_combine(&table, unused_index, unused_index));
>   }

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