[PATCH] rockchip/drm: vop2: make vp registers nonvolatile

[Andy Yan]

Hello Piotr,

At 2025-06-29 02:11:00, "Piotr Zalewski" <pZ010001011111 at proton.me> wrote:
>Make video port registers nonvolatile. As DSP_CTRL register is written
>to twice due to gamma LUT enable bit which is set outside of the main
>DSP_CTRL initialization within atomic_enable (for rk356x case it is also
>necesarry to always disable gamma LUT before writing a new LUT) there is
>a chance that DSP_CTRL value read-out in gamma LUT init/update code is
>not the one which was written by the preceding DSP_CTRL initialization
>code within atomic_enable. This might result in misconfigured DSP_CTRL
>which leads to no visual output[1]. Since DSP_CTRL write takes effect
>after VSYNC[1] the issue is not always present. When tested on Pinetab2
>with kernel 6.14 it happenes only when DRM is compiled as a module[1].
>In order to confirm that it is because of timing I inserted 18ms udelay
>before vop2_crtc_atomic_try_set_gamma in atomic enable and compiled DRM
>as module - this has also fixed the issue on Pinetab2.
>
>[1] https://lore.kernel.org/linux-rockchip/562b38e5.a496.1975f09f983.Coremail.andyshrk@163.com/
>
>Reported-by: Diederik de Haas <didi.debian at cknow.org>
>Closes: https://lore.kernel.org/linux-rockchip/DAEVDSTMWI1E.J454VZN0R9MA@cknow.org/
>Suggested-by: Andy Yan <andy.yan at rock-chips.com>
>Signed-off-by: Piotr Zalewski <pZ010001011111 at proton.me>
>---
> drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>index d0f5fea15e21..241060cc24cb 100644
>--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
>@@ -2589,12 +2589,13 @@ static int vop2_win_init(struct vop2 *vop2)
> }
> 
> /*
>- * The window registers are only updated when config done is written.
>- * Until that they read back the old value. As we read-modify-write
>- * these registers mark them as non-volatile. This makes sure we read
>- * the new values from the regmap register cache.
>+ * The window and video port registers are only updated when config
>+ * done is written. Until that they read back the old value. As we
>+ * read-modify-write these registers mark them as non-volatile. This
>+ * makes sure we read the new values from the regmap register cache.
>  */
> static const struct regmap_range vop2_nonvolatile_range[] = {
>+	regmap_reg_range(RK3568_VP0_CTRL_BASE, RK3588_VP3_CTRL_BASE+255),

Small nit: there should be spaces before and after the  + 

> 	regmap_reg_range(0x1000, 0x23ff),
> };
> 
>-- 
>2.50.0
>
>