Re: [PATCH v2] rockchip/drm: vop2: make vp registers nonvolatile

["Diederik de Haas" <didi.debian@cknow.org>]

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Hi Piotr,

On Sun Jul 6, 2025 at 10:36 AM CEST, Piotr Zalewski 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 a timing issue 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.
>
> [1] https://lore.kernel.org/linux-rockchip/562b38e5.a496.1975f09f983.Coremail.andyshrk@163.com/
>
> Reported-by: Diederik de Haas <didi.debian@cknow.org>
> Closes: https://lore.kernel.org/linux-rockchip/DAEVDSTMWI1E.J454VZN0R9MA@cknow.org/
> Suggested-by: Andy Yan <andy.yan@rock-chips.com>
> Signed-off-by: Piotr Zalewski <pZ010001011111@proton.me>

With a new version of a patch, you're supposed to add the tags you
received for previous versions, like my Tested-by tag [1].

(unless the new version has changed so much you feel they should not be
carried over; you then need to explicitly describe that and why you
dropped them)

Cheers,
  Diederik

[1] https://lore.kernel.org/linux-rockchip/DAZ4BALHEJ9M.10FO1U9IYP4WA@cknow.org/

> ---
>
> Notes:
>     Changes in v2:
>         - add spaces before and after '+'
>     
>     Link to v1: https://lore.kernel.org/linux-rockchip/20250628180914.1177177-2-pZ010001011111@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..0931cb636493 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),
>  	regmap_reg_range(0x1000, 0x23ff),
>  };
>  


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