[PATCH v2 1/6] drm/vc4: Make vc4_lbm_size() return 0 when vertical scaling is disabled

[Boris Brezillon]

On Fri, 30 Nov 2018 10:02:49 +0100
Boris Brezillon <boris.brezillon at bootlin.com> wrote:

> LBM is not needed when vertical scaling is disabled. Return 0 in this
> case to avoid allocating LBM memory that will anyway be unused.
> 
> While at it, drop the test on ->is_unity which is now redundant.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
> Reviewed-by: Eric Anholt <eric at anholt.net>

Queued the series to drm-misc-next.

> ---
> Changes in v2:
> - Add Eric R-b
> ---
>  drivers/gpu/drm/vc4/vc4_plane.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index c3ded0ba0441..f6e3e8d33115 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -395,10 +395,13 @@ static u32 vc4_lbm_size(struct drm_plane_state *state)
>  	u32 pix_per_line = max(vc4_state->src_w[0], (u32)vc4_state->crtc_w);
>  	u32 lbm;
>  
> +	/* LBM is not needed when there's no vertical scaling. */
> +	if (vc4_state->y_scaling[0] == VC4_SCALING_NONE &&
> +	    vc4_state->y_scaling[1] == VC4_SCALING_NONE)
> +		return 0;
> +
>  	if (!vc4_state->is_yuv) {
> -		if (vc4_state->is_unity)
> -			return 0;
> -		else if (vc4_state->y_scaling[0] == VC4_SCALING_TPZ)
> +		if (vc4_state->y_scaling[0] == VC4_SCALING_TPZ)
>  			lbm = pix_per_line * 8;
>  		else {
>  			/* In special cases, this multiplier might be 12. */