From 6820b2b01d69ac316786570a592cc32efc559a0e Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Mon, 3 Dec 2018 14:24:36 -0800 Subject: [PATCH 576/703] drm/v3d: Drop the wait for L2T flush to complete. According to Dave, once you've started an L2T flush, all L2T accesses will be blocked until the flush completes. This fixes a consistent 3-4ms stall between the ioctl and running the job, and 3DMMES Taiji goes from 27fps to 110fps. v2: Leave a note about why we don't need to wait for completion. Signed-off-by: Eric Anholt Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+") Reviewed-by: Dave Emett Link: https://patchwork.freedesktop.org/patch/msgid/20181203222438.25417-4-eric@anholt.net (cherry picked from commit 51c1b6f9eb3dbdec91b0e3c89f623e634c996bbb) --- drivers/gpu/drm/v3d/v3d_gem.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/gpu/drm/v3d/v3d_gem.c +++ b/drivers/gpu/drm/v3d/v3d_gem.c @@ -143,13 +143,13 @@ v3d_invalidate_l2(struct v3d_dev *v3d, i static void v3d_flush_l2t(struct v3d_dev *v3d, int core) { + /* While there is a busy bit (V3D_L2TCACTL_L2TFLS), we don't + * need to wait for completion before dispatching the job -- + * L2T accesses will be stalled until the flush has completed. + */ V3D_CORE_WRITE(core, V3D_CTL_L2TCACTL, V3D_L2TCACTL_L2TFLS | V3D_SET_FIELD(V3D_L2TCACTL_FLM_FLUSH, V3D_L2TCACTL_FLM)); - if (wait_for(!(V3D_CORE_READ(core, V3D_CTL_L2TCACTL) & - V3D_L2TCACTL_L2TFLS), 100)) { - DRM_ERROR("Timeout waiting for L2T flush\n"); - } } /* Invalidates the slice caches. These are read-only caches. */