Re: [PATCH] drm/rockchip: vop2: fix suspend/resume

[Chris Morgan <macroalpha82@gmail.com>]

On Thu, Apr 13, 2023 at 04:43:47PM +0200, Sascha Hauer wrote:
> During a suspend/resume cycle the VO power domain will be disabled and
> the VOP2 registers will reset to their default values. After that the
> cached register values will be out of sync and the read/modify/write
> operations we do on the window registers will result in bogus values
> written. Fix this by re-initializing the register cache each time we
> enable the VOP2. With this the VOP2 will show a picture after a
> suspend/resume cycle whereas without this the screen stays dark.
> 
> Fixes: 604be85547ce4 ("drm/rockchip: Add VOP2 driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> index ba3b817895091..d9daa686b014d 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> @@ -215,6 +215,8 @@ struct vop2 {
>  	struct vop2_win win[];
>  };
>  
> +static const struct regmap_config vop2_regmap_config;
> +
>  static struct vop2_video_port *to_vop2_video_port(struct drm_crtc *crtc)
>  {
>  	return container_of(crtc, struct vop2_video_port, crtc);
> @@ -839,6 +841,12 @@ static void vop2_enable(struct vop2 *vop2)
>  		return;
>  	}
>  
> +	ret = regmap_reinit_cache(vop2->map, &vop2_regmap_config);
> +	if (ret) {
> +		drm_err(vop2->drm, "failed to reinit cache: %d\n", ret);
> +		return;
> +	}
> +
>  	if (vop2->data->soc_id == 3566)
>  		vop2_writel(vop2, RK3568_OTP_WIN_EN, 1);
>  
> -- 
> 2.39.2
> 

I confirmed this works on my Anbernic RG353P which uses the rk3566 SOC.
Before applying the patch I displayed a color pattern with modetest
before suspend and it appeared correctly. Then I suspended and resumed
the device, attempted to display the same color pattern, and only got
a single pixel on an otherwise blank display. After applying the patch
I performed the same test and the color pattern appeared correctly
both before and after suspend (and the display was no longer blank
after resume from suspend).

Tested-by: Chris Morgan <macromorgan@hotmail.com>

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