Re: [PATCH 2/6] drm/i915: Add macro for SSEU stride calculation

[Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>]

On 5/1/19 8:34 AM, Stuart Summers wrote:
> Subslice stride and EU stride are calculated multiple times in
> i915_query. Move this calculation to a macro to reduce code duplication.
>
> v2: update headers in intel_sseu.h
>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> Signed-off-by: Stuart Summers <stuart.summers@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/gt/intel_sseu.h |  2 ++
>   drivers/gpu/drm/i915/i915_query.c    | 17 ++++++++---------
>   2 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_sseu.h b/drivers/gpu/drm/i915/gt/intel_sseu.h
> index 73bc824094e8..c0b16b248d4c 100644
> --- a/drivers/gpu/drm/i915/gt/intel_sseu.h
> +++ b/drivers/gpu/drm/i915/gt/intel_sseu.h
> @@ -8,11 +8,13 @@
>   #define __INTEL_SSEU_H__
>   
>   #include <linux/types.h>
> +#include <linux/kernel.h>
>   
>   struct drm_i915_private;
>   
>   #define GEN_MAX_SLICES		(6) /* CNL upper bound */
>   #define GEN_MAX_SUBSLICES	(8) /* ICL upper bound */
> +#define GEN_SSEU_STRIDE(bits) DIV_ROUND_UP(bits, BITS_PER_BYTE)

What we pass to this macro isn't really a bits count but the maximum 
amount of s/ss/eus. s/bits/max_entry/, or something like that? with that:

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>

Daniele

>   
>   struct sseu_dev_info {
>   	u8 slice_mask;
> diff --git a/drivers/gpu/drm/i915/i915_query.c b/drivers/gpu/drm/i915/i915_query.c
> index 782183b78f49..7c1708c22811 100644
> --- a/drivers/gpu/drm/i915/i915_query.c
> +++ b/drivers/gpu/drm/i915/i915_query.c
> @@ -37,6 +37,8 @@ static int query_topology_info(struct drm_i915_private *dev_priv,
>   	const struct sseu_dev_info *sseu = &RUNTIME_INFO(dev_priv)->sseu;
>   	struct drm_i915_query_topology_info topo;
>   	u32 slice_length, subslice_length, eu_length, total_length;
> +	u8 subslice_stride = GEN_SSEU_STRIDE(sseu->max_subslices);
> +	u8 eu_stride = GEN_SSEU_STRIDE(sseu->max_eus_per_subslice);
>   	int ret;
>   
>   	if (query_item->flags != 0)
> @@ -48,12 +50,10 @@ static int query_topology_info(struct drm_i915_private *dev_priv,
>   	BUILD_BUG_ON(sizeof(u8) != sizeof(sseu->slice_mask));
>   
>   	slice_length = sizeof(sseu->slice_mask);
> -	subslice_length = sseu->max_slices *
> -		DIV_ROUND_UP(sseu->max_subslices, BITS_PER_BYTE);
> -	eu_length = sseu->max_slices * sseu->max_subslices *
> -		DIV_ROUND_UP(sseu->max_eus_per_subslice, BITS_PER_BYTE);
> -
> -	total_length = sizeof(topo) + slice_length + subslice_length + eu_length;
> +	subslice_length = sseu->max_slices * subslice_stride;
> +	eu_length = sseu->max_slices * sseu->max_subslices * eu_stride;
> +	total_length = sizeof(topo) + slice_length + subslice_length +
> +		       eu_length;
>   
>   	ret = copy_query_item(&topo, sizeof(topo), total_length,
>   			      query_item);
> @@ -69,10 +69,9 @@ static int query_topology_info(struct drm_i915_private *dev_priv,
>   	topo.max_eus_per_subslice = sseu->max_eus_per_subslice;
>   
>   	topo.subslice_offset = slice_length;
> -	topo.subslice_stride = DIV_ROUND_UP(sseu->max_subslices, BITS_PER_BYTE);
> +	topo.subslice_stride = subslice_stride;
>   	topo.eu_offset = slice_length + subslice_length;
> -	topo.eu_stride =
> -		DIV_ROUND_UP(sseu->max_eus_per_subslice, BITS_PER_BYTE);
> +	topo.eu_stride = eu_stride;
>   
>   	if (__copy_to_user(u64_to_user_ptr(query_item->data_ptr),
>   			   &topo, sizeof(topo)))
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