linux-kernel - Re: [PATCH 3/6] drm/v3d: Don't bother flushing L1TD at job start.

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Date:   Mon, 3 Dec 2018 17:36:25 +0000
From:   Dave Emett <david.emett@...adcom.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Thomas Spurden <thomas.spurden@...adcom.com>
Subject: Re: [PATCH 3/6] drm/v3d: Don't bother flushing L1TD at job start.

On Sat, 1 Dec 2018 at 00:58, Eric Anholt <eric@...olt.net> wrote:
>
> This is the write combiner for TMU writes.  You're supposed to flush
> that at job end if you had dirtied any cachelines.  Flushing it at job
> start then doesn't make any sense.
>
> Signed-off-by: Eric Anholt <eric@...olt.net>

Reviewed-by: Dave Emett <david.emett@...adcom.com>

> Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")
> ---
>  drivers/gpu/drm/v3d/v3d_gem.c | 12 ------------
>  1 file changed, 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index 34103205b7cb..cc4d025b01e0 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -139,22 +139,10 @@ v3d_invalidate_l2(struct v3d_dev *v3d, int core)
>                        V3D_L2CACTL_L2CENA);
>  }
>
> -static void
> -v3d_invalidate_l1td(struct v3d_dev *v3d, int core)
> -{
> -       V3D_CORE_WRITE(core, V3D_CTL_L2TCACTL, V3D_L2TCACTL_TMUWCF);
> -       if (wait_for(!(V3D_CORE_READ(core, V3D_CTL_L2TCACTL) &
> -                      V3D_L2TCACTL_L2TFLS), 100)) {
> -               DRM_ERROR("Timeout waiting for L1T write combiner flush\n");
> -       }
> -}
> -
>  /* Invalidates texture L2 cachelines */
>  static void
>  v3d_flush_l2t(struct v3d_dev *v3d, int core)
>  {
> -       v3d_invalidate_l1td(v3d, core);
> -
>         V3D_CORE_WRITE(core, V3D_CTL_L2TCACTL,
>                        V3D_L2TCACTL_L2TFLS |
>                        V3D_SET_FIELD(V3D_L2TCACTL_FLM_FLUSH, V3D_L2TCACTL_FLM));
> --
> 2.20.0.rc1
>