The RK3066 VOP sets a dma_stop bit when it's done scanning out a frame and needs the driver to acknowledge that by clearing the bit.
Unless we clear it "between" frames, the RGB output only shows noise instead of the picture. atomic_flush is the place for it that least affects other code (doing it on vblank would require converting all other usages of the reg_lock to spin_(un)lock_irq, which would affect performance for everyone).
This seems to be a redundant synchronization mechanism that was removed in later iterations of the VOP hardware block.
Fixes: f4a6de8 ("drm: rockchip: vop: add rk3066 vop definitions") Cc: stable@vger.kernel.org Signed-off-by: Val Packett val@packett.cool --- drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 4 ++++ drivers/gpu/drm/rockchip/rockchip_drm_vop.h | 1 + drivers/gpu/drm/rockchip/rockchip_vop_reg.c | 1 + 3 files changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c index a13473b2d..e88fbd568 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c @@ -1583,6 +1583,10 @@ static void vop_crtc_atomic_flush(struct drm_crtc *crtc, VOP_AFBC_SET(vop, enable, s->enable_afbc); vop_cfg_done(vop);
+ /* Ack the DMA transfer of the previous frame (RK3066). */ + if (VOP_HAS_REG(vop, common, dma_stop)) + VOP_REG_SET(vop, common, dma_stop, 0); + spin_unlock(&vop->reg_lock);
/* diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h index b33e5bdc2..0cf512cc1 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h @@ -122,6 +122,7 @@ struct vop_common { struct vop_reg lut_buffer_index; struct vop_reg gate_en; struct vop_reg mmu_en; + struct vop_reg dma_stop; struct vop_reg out_mode; struct vop_reg standby; }; diff --git a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c index b9ee02061..9bcb40a64 100644 --- a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c +++ b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c @@ -466,6 +466,7 @@ static const struct vop_output rk3066_output = { };
static const struct vop_common rk3066_common = { + .dma_stop = VOP_REG(RK3066_SYS_CTRL0, 0x1, 0), .standby = VOP_REG(RK3066_SYS_CTRL0, 0x1, 1), .out_mode = VOP_REG(RK3066_DSP_CTRL0, 0xf, 0), .cfg_done = VOP_REG(RK3066_REG_CFG_DONE, 0x1, 0),