On Mon, May 27 2024 at 20:11:49 -03:00:00, Val Packett
<val@xxxxxxxxxxxx> wrote:
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.
So unless we clear it "between" frames, the RGB output only shows
noise
instead of the picture. vblank seems to be the most appropriate place
to
do it, since it indicates exactly that: that the hardware is done
with the frame.
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@xxxxxxxxxxxxxxx
Signed-off-by: Val Packett <val@xxxxxxxxxxxx>
---
drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 6 ++++++
drivers/gpu/drm/rockchip/rockchip_drm_vop.h | 1 +
drivers/gpu/drm/rockchip/rockchip_vop_reg.c | 1 +
3 files changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index a13473b2d..2731fe2b2 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1766,6 +1766,12 @@ static void vop_handle_vblank(struct vop *vop)
}
spin_unlock(&drm->event_lock);
+ if (VOP_HAS_REG(vop, common, dma_stop)) {
+ spin_lock(&vop->reg_lock);
+ VOP_REG_SET(vop, common, dma_stop, 0);
+ spin_unlock(&vop->reg_lock);
+ }
+
Oops… so doing it here actually causes deadlocks, unless we also
change all other reg_lock usages to be spin_lock_irq/spin_unlock_irq.
Not sure if doing that or going back to v1 would be better.
