Re: [PATCH] drm/i915/skl: Remove unnecessary local variables in skl_plane_ctl*()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, May 12, 2015 at 06:53:22PM +0100, Damien Lespiau wrote:
> Ville noticed in another patch we we didn't need them at all, so remove
> them. It's worth saying that it makes no difference to code generated as
> gcc is clever enough to optimize it out.
> 
> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 48 ++++++++++++++++--------------------
>  1 file changed, 21 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 23765d2..75ab299 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2953,20 +2953,18 @@ void skl_detach_scalers(struct intel_crtc *intel_crtc)
>  
>  u32 skl_plane_ctl_format(uint32_t pixel_format)
>  {
> -	u32 format = 0;
> -
>  	switch (pixel_format) {
>  	case DRM_FORMAT_C8:
> -		format = PLANE_CTL_FORMAT_INDEXED;
> +		return PLANE_CTL_FORMAT_INDEXED;
>  		break;

Can kill all the breaks too (with a few return 0's added)

With those changes this gets
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

>  	case DRM_FORMAT_RGB565:
> -		format = PLANE_CTL_FORMAT_RGB_565;
> +		return PLANE_CTL_FORMAT_RGB_565;
>  		break;
>  	case DRM_FORMAT_XBGR8888:
> -		format = PLANE_CTL_FORMAT_XRGB_8888 | PLANE_CTL_ORDER_RGBX;
> +		return PLANE_CTL_FORMAT_XRGB_8888 | PLANE_CTL_ORDER_RGBX;
>  		break;
>  	case DRM_FORMAT_XRGB8888:
> -		format = PLANE_CTL_FORMAT_XRGB_8888;
> +		return PLANE_CTL_FORMAT_XRGB_8888;
>  		break;
>  	/*
>  	 * XXX: For ARBG/ABGR formats we default to expecting scanout buffers
> @@ -2974,82 +2972,78 @@ u32 skl_plane_ctl_format(uint32_t pixel_format)
>  	 * DRM_FORMAT) for user-space to configure that.
>  	 */
>  	case DRM_FORMAT_ABGR8888:
> -		format = PLANE_CTL_FORMAT_XRGB_8888 | PLANE_CTL_ORDER_RGBX |
> +		return PLANE_CTL_FORMAT_XRGB_8888 | PLANE_CTL_ORDER_RGBX |
>  			PLANE_CTL_ALPHA_SW_PREMULTIPLY;
>  		break;
>  	case DRM_FORMAT_ARGB8888:
> -		format = PLANE_CTL_FORMAT_XRGB_8888 |
> +		return PLANE_CTL_FORMAT_XRGB_8888 |
>  			PLANE_CTL_ALPHA_SW_PREMULTIPLY;
>  		break;
>  	case DRM_FORMAT_XRGB2101010:
> -		format = PLANE_CTL_FORMAT_XRGB_2101010;
> +		return PLANE_CTL_FORMAT_XRGB_2101010;
>  		break;
>  	case DRM_FORMAT_XBGR2101010:
> -		format = PLANE_CTL_ORDER_RGBX | PLANE_CTL_FORMAT_XRGB_2101010;
> +		return PLANE_CTL_ORDER_RGBX | PLANE_CTL_FORMAT_XRGB_2101010;
>  		break;
>  	case DRM_FORMAT_YUYV:
> -		format = PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_YUYV;
> +		return PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_YUYV;
>  		break;
>  	case DRM_FORMAT_YVYU:
> -		format = PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_YVYU;
> +		return PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_YVYU;
>  		break;
>  	case DRM_FORMAT_UYVY:
> -		format = PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_UYVY;
> +		return PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_UYVY;
>  		break;
>  	case DRM_FORMAT_VYUY:
> -		format = PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_VYUY;
> +		return PLANE_CTL_FORMAT_YUV422 | PLANE_CTL_YUV422_VYUY;
>  		break;
>  	default:
>  		MISSING_CASE(pixel_format);
>  	}
>  
> -	return format;
> +	return 0;
>  }
>  
>  u32 skl_plane_ctl_tiling(uint64_t fb_modifier)
>  {
> -	u32 plane_ctl_tiling = 0;
> -
>  	switch (fb_modifier) {
>  	case DRM_FORMAT_MOD_NONE:

return 0

>  		break;
>  	case I915_FORMAT_MOD_X_TILED:
> -		plane_ctl_tiling = PLANE_CTL_TILED_X;
> +		return PLANE_CTL_TILED_X;
>  		break;
>  	case I915_FORMAT_MOD_Y_TILED:
> -		plane_ctl_tiling = PLANE_CTL_TILED_Y;
> +		return PLANE_CTL_TILED_Y;
>  		break;
>  	case I915_FORMAT_MOD_Yf_TILED:
> -		plane_ctl_tiling = PLANE_CTL_TILED_YF;
> +		return PLANE_CTL_TILED_YF;
>  		break;
>  	default:
>  		MISSING_CASE(fb_modifier);
>  	}
>  
> -	return plane_ctl_tiling;
> +	return 0;
>  }
>  
>  u32 skl_plane_ctl_rotation(unsigned int rotation)
>  {
> -	u32 plane_ctl_rotation = 0;
> -
>  	switch (rotation) {
>  	case BIT(DRM_ROTATE_0):

return 0

>  		break;
>  	case BIT(DRM_ROTATE_90):
> -		plane_ctl_rotation = PLANE_CTL_ROTATE_90;
> +		return PLANE_CTL_ROTATE_90;
>  		break;
>  	case BIT(DRM_ROTATE_180):
> -		plane_ctl_rotation = PLANE_CTL_ROTATE_180;
> +		return PLANE_CTL_ROTATE_180;
>  		break;
>  	case BIT(DRM_ROTATE_270):
> -		plane_ctl_rotation = PLANE_CTL_ROTATE_270;
> +		return PLANE_CTL_ROTATE_270;
>  		break;
>  	default:
>  		MISSING_CASE(rotation);
>  	}
>  
> -	return plane_ctl_rotation;
> +	return 0;
>  }
>  
>  static void skylake_update_primary_plane(struct drm_crtc *crtc,
> -- 
> 2.1.0
> 
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-- 
Ville Syrjälä
Intel OTC
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