Re: [PATCH 2/9] drm/rockchip: vop2: Reset AXI and DCLK to improve robustness

["Diederik de Haas" <diederik@cknow-tech.com>]

Hi Cristian,

On Wed Jun 17, 2026 at 8:52 PM CEST, Cristian Ciocaltea wrote:
> Assert the AXI reset in the CRTC disable path, and the VP DCLK reset in
> the enable path.
>
> These resets are intended to leave the hardware in a clean state for the
> next use, helping recover from exceptions such as IOMMU page faults, as
> well as to prevent random display output glitches, such as a blank
> image, observed when switching modes that also change the color format,
> e.g. from RGB to YUV420 and vice versa.
>
> For now this seems to affect only the RK3588, hence the resets are
> optional and will be provided in the device tree for this SoC only.

Why do you think it only effect RK3588? I reported about my RK3568 test here:
https://lore.kernel.org/linux-rockchip/DFRU6ODDM71P.3NQGLRK8IVDUY@cknow-tech.com/
"I then went on to try LibreELEC's builds. The artifacts I (sometimes)
saw, were gone :-D OTOH, I did get several major issues 'in return',
like rk_iommu Page fault resulting in a black screen and the only way to
'recover' from it, was a reboot."

And I reported some more test results here:
https://forum.libreelec.tv/thread/29953-le13-testing-for-rk3288-rk3328-rk3399-rk3566-rk3568-rk3576-rk3588/?postID=204691#post204691

That seems to me a (strong) indication it also affects RK3566/RK3568?

Cheers,
  Diederik

> Co-developed-by: Andy Yan <andy.yan@rock-chips.com>
> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 35 ++++++++++++++++++++++++++++
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.h |  4 ++++
>  2 files changed, 39 insertions(+)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> index 4cce3e336f5b..2833fb49ad81 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> @@ -17,6 +17,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/regmap.h>
> +#include <linux/reset.h>
>  #include <linux/swab.h>
>  
>  #include <drm/drm.h>
> @@ -860,6 +861,26 @@ static int vop2_core_clks_prepare_enable(struct vop2 *vop2)
>  	return ret;
>  }
>  
> +static void vop2_clk_reset(struct vop2 *vop2, struct reset_control *rstc)
> +{
> +	int ret;
> +
> +	if (!rstc)
> +		return;
> +
> +	ret = reset_control_assert(rstc);
> +	if (ret < 0) {
> +		drm_warn(vop2->drm, "failed to assert reset: %d\n", ret);
> +		return;
> +	}
> +
> +	udelay(10);
> +
> +	ret = reset_control_deassert(rstc);
> +	if (ret < 0)
> +		drm_err(vop2->drm, "failed to deassert reset: %d\n", ret);
> +}
> +
>  static void rk3588_vop2_power_domain_enable_all(struct vop2 *vop2)
>  {
>  	u32 pd;
> @@ -938,6 +959,8 @@ static void vop2_disable(struct vop2 *vop2)
>  {
>  	rockchip_drm_dma_detach_device(vop2->drm, vop2->dev);
>  
> +	vop2_clk_reset(vop2, vop2->axi_rst);
> +
>  	pm_runtime_put_sync(vop2->dev);
>  
>  	regcache_drop_region(vop2->map, 0, vop2_regmap_config.max_register);
> @@ -1948,6 +1971,8 @@ static void vop2_crtc_atomic_enable(struct drm_crtc *crtc,
>  
>  	vop2_crtc_atomic_try_set_gamma(vop2, vp, crtc, crtc_state);
>  
> +	vop2_clk_reset(vop2, vp->dclk_rst);
> +
>  	drm_crtc_vblank_on(crtc);
>  
>  	vop2_unlock(vop2);
> @@ -2531,6 +2556,11 @@ static int vop2_create_crtcs(struct vop2 *vop2)
>  			return dev_err_probe(drm->dev, PTR_ERR(vp->dclk),
>  					     "failed to get %s\n", dclk_name);
>  
> +		vp->dclk_rst = devm_reset_control_get_optional(vop2->dev, dclk_name);
> +		if (IS_ERR(vp->dclk_rst))
> +			return dev_err_probe(drm->dev, PTR_ERR(vp->dclk_rst),
> +					     "failed to get %s reset\n", dclk_name);
> +
>  		np = of_graph_get_remote_node(dev->of_node, i, -1);
>  		if (!np) {
>  			drm_dbg(vop2->drm, "%s: No remote for vp%d\n", __func__, i);
> @@ -2890,6 +2920,11 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
>  		return dev_err_probe(drm->dev, PTR_ERR(vop2->pll_hdmiphy1),
>  				     "failed to get pll_hdmiphy1\n");
>  
> +	vop2->axi_rst = devm_reset_control_get_optional(vop2->dev, "axi");
> +	if (IS_ERR(vop2->axi_rst))
> +		return dev_err_probe(drm->dev, PTR_ERR(vop2->axi_rst),
> +				     "failed to get axi reset\n");
> +
>  	vop2->irq = platform_get_irq(pdev, 0);
>  	if (vop2->irq < 0)
>  		return dev_err_probe(drm->dev, vop2->irq, "cannot find irq for vop2\n");
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
> index ffcb39c130aa..14b437d2d088 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
> @@ -165,6 +165,8 @@ enum vop2_win_regs {
>  	VOP2_WIN_MAX_REG,
>  };
>  
> +struct reset_control;
> +
>  struct vop2_regs_dump {
>  	const char *name;
>  	u32 base;
> @@ -238,6 +240,7 @@ struct vop2_video_port {
>  	struct vop2 *vop2;
>  	struct clk *dclk;
>  	struct clk *dclk_src;
> +	struct reset_control *dclk_rst;
>  	unsigned int id;
>  	const struct vop2_video_port_data *data;
>  
> @@ -329,6 +332,7 @@ struct vop2 {
>  	struct clk *pclk;
>  	struct clk *pll_hdmiphy0;
>  	struct clk *pll_hdmiphy1;
> +	struct reset_control *axi_rst;
>  
>  	/* optional internal rgb encoder */
>  	struct rockchip_rgb *rgb;