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

[Philipp Zabel]

On Mi, 2026-06-17 at 21:51 +0300, 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.
> 
> Co-developed-by: Andy Yan <andy.yan at rock-chips.com>
> Signed-off-by: Andy Yan <andy.yan at rock-chips.com>
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea at 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)

The _clk part of the function name is misleading ...

[...]
> @@ -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);

... because this function is also called with the AXI reset control.

> +
>  	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);

Please use devm_reset_control_get_optional_exclusive() directly.

> +		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");

Same as above, devm_reset_control_get_optional_exclusive().

regards
Philipp