On Thu, 21 Dec 2017 14:17:22 -0800
Eric Anholt <e...@anholt.net> wrote:
> If the frame samples from a render target that was just written, its
> cache flush during the binning step may have occurred before the
> previous frame's RCL was completed. Flush the texture caches again
> before starting each RCL job to make sure that the sampling of the
> previous RCL's output is correct.
>
> Fixes flickering in the top left of 3DMMES Taiji.
>
> Signed-off-by: Eric Anholt <e...@anholt.net>
> Fixes: ca26d28bbaa3 ("drm/vc4: improve throughput by pipelining binning and
> rendering jobs")
Reviewed-by: Boris Brezillon <boris.brezil...@free-electrons.com>
> ---
> drivers/gpu/drm/vc4/vc4_gem.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
> index 6c32c89a83a9..afa7fe21b35e 100644
> --- a/drivers/gpu/drm/vc4/vc4_gem.c
> +++ b/drivers/gpu/drm/vc4/vc4_gem.c
> @@ -436,6 +436,19 @@ vc4_flush_caches(struct drm_device *dev)
> VC4_SET_FIELD(0xf, V3D_SLCACTL_ICC));
> }
>
> +static void
> +vc4_flush_texture_caches(struct drm_device *dev)
> +{
> + struct vc4_dev *vc4 = to_vc4_dev(dev);
> +
> + V3D_WRITE(V3D_L2CACTL,
> + V3D_L2CACTL_L2CCLR);
> +
> + V3D_WRITE(V3D_SLCACTL,
> + VC4_SET_FIELD(0xf, V3D_SLCACTL_T1CC) |
> + VC4_SET_FIELD(0xf, V3D_SLCACTL_T0CC));
> +}
> +
> /* Sets the registers for the next job to be actually be executed in
> * the hardware.
> *
> @@ -474,6 +487,14 @@ vc4_submit_next_render_job(struct drm_device *dev)
> if (!exec)
> return;
>
> + /* A previous RCL may have written to one of our textures, and
> + * our full cache flush at bin time may have occurred before
> + * that RCL completed. Flush the texture cache now, but not
> + * the instructions or uniforms (since we don't write those
> + * from an RCL).
> + */
> + vc4_flush_texture_caches(dev);
> +
> submit_cl(dev, 1, exec->ct1ca, exec->ct1ea);
> }
>
