[Intel-gfx] [PATCH 02/11] drm/i915: remove padding from struct skl_wm_level

[Lucas De Marchi]

On Tue, Oct 16, 2018 at 03:01:24PM -0700, Paulo Zanoni wrote:
> This reduces the size of struct skl_wm_level from 6 to 4, which
> reduces the size of struct skl_plane_wm from 104 to 70, which reduces
> the size of struct skl_pipe_wm from 524 to 356. A reduction of 168
> padding bytes per pipe. This will increase even more the next time we
> bump I915_MAX_PLANES.
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

For completeness:

$ pahole -s -C skl_wm_level drivers/gpu/drm/i915/i915.o
struct skl_wm_level {
	bool                       plane_en;             /*     0     1 */

	/* XXX 1 byte hole, try to pack */

	uint16_t                   plane_res_b;          /*     2     2 */
	uint8_t                    plane_res_l;          /*     4     1 */

	/* size: 6, cachelines: 1, members: 3 */
	/* sum members: 4, holes: 1, sum holes: 1 */
	/* padding: 1 */
	/* last cacheline: 6 bytes */
};

So yes, this removes the padding and hole that are there due to alignment.

Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>

Lucas De Marchi

> ---
>  drivers/gpu/drm/i915/i915_drv.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 3017ef037fed..3616b718b5d2 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1243,9 +1243,9 @@ struct skl_ddb_values {
>  };
>  
>  struct skl_wm_level {
> -	bool plane_en;
>  	uint16_t plane_res_b;
>  	uint8_t plane_res_l;
> +	bool plane_en;
>  };
>  
>  /* Stores plane specific WM parameters */
> -- 
> 2.14.4
> 
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