On the RK3066, there is a bit that must be cleared on flush, otherwise we do not get display output (at least for RGB).
Signed-off-by: Val Packett val@packett.cool Cc: stable@vger.kernel.org --- Hi! This was required to get display working on an old RK3066 tablet, along with the next tiny patch in the series enabling the RGB output.
I have spent quite a lot of time banging my head against the wall debugging that display (especially since at the same time a scaler chip is used for LVDS encoding), but finally adding debug prints showed that RK3066_SYS_CTRL0 ended up being reset to all-zero after being written correctly upon init. Looking at the register definitions in the vendor driver revealed that the reason was pretty self-explanatory: "dma_stop". --- drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 3 +++ drivers/gpu/drm/rockchip/rockchip_drm_vop.h | 1 + drivers/gpu/drm/rockchip/rockchip_vop_reg.c | 1 + 3 files changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c index a13473b2d..d4daeba74 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c @@ -1578,6 +1578,9 @@ static void vop_crtc_atomic_flush(struct drm_crtc *crtc,
spin_lock(&vop->reg_lock);
+ /* If the chip has a DMA stop bit (RK3066), it must be cleared. */ + VOP_REG_SET(vop, common, dma_stop, 0); + /* Enable AFBC if there is some AFBC window, disable otherwise. */ s = to_rockchip_crtc_state(crtc->state); VOP_AFBC_SET(vop, enable, s->enable_afbc); 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),