Re: [PATCH 1/2] drm/kmb: reset DSI host singleton state on teardown

[Osama Abdelkader <osama.abdelkader@gmail.com>]

On Mon, Apr 20, 2026 at 05:06:57PM +0200, Osama Abdelkader wrote:
> Tear down and clear the global DSI host/device/bridge singleton state
> when unregistering the host so probe retries and remove/reprobe cycles
> start from a clean state.
> 
> Guard the clock-disable path in kmb_dsi_host_unregister() to avoid
> dereferencing error pointers from early probe failure paths.
> Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
> ---
>  drivers/gpu/drm/kmb/kmb_dsi.c | 44 ++++++++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/kmb/kmb_dsi.c b/drivers/gpu/drm/kmb/kmb_dsi.c
> index aeb2f9f98f23..500dc00ba6ae 100644
> --- a/drivers/gpu/drm/kmb/kmb_dsi.c
> +++ b/drivers/gpu/drm/kmb/kmb_dsi.c
> @@ -5,6 +5,7 @@
>  
>  #include <linux/clk.h>
>  #include <linux/delay.h>
> +#include <linux/err.h>
>  #include <linux/of.h>
>  #include <linux/of_graph.h>
>  #include <linux/mfd/syscon.h>
> @@ -182,8 +183,18 @@ static void kmb_dsi_clk_disable(struct kmb_dsi *kmb_dsi)
>  
>  void kmb_dsi_host_unregister(struct kmb_dsi *kmb_dsi)
>  {
> -	kmb_dsi_clk_disable(kmb_dsi);
> -	mipi_dsi_host_unregister(kmb_dsi->host);
> +	if (!IS_ERR_OR_NULL(kmb_dsi))
> +		kmb_dsi_clk_disable(kmb_dsi);
> +
> +	if (dsi_host) {
> +		mipi_dsi_host_unregister(dsi_host);
> +		kfree(dsi_host);
> +		dsi_host = NULL;
> +	}
> +
> +	kfree(dsi_device);
> +	dsi_device = NULL;
> +	adv_bridge = NULL;
>  }
>  
>  /*
> @@ -217,6 +228,8 @@ static const struct mipi_dsi_host_ops kmb_dsi_host_ops = {
>  int kmb_dsi_host_bridge_init(struct device *dev)
>  {
>  	struct device_node *encoder_node, *dsi_out;
> +	bool host_registered = false;
> +	int ret;
>  
>  	/* Create and register MIPI DSI host */
>  	if (!dsi_host) {
> @@ -230,25 +243,38 @@ int kmb_dsi_host_bridge_init(struct device *dev)
>  			dsi_device = kzalloc_obj(*dsi_device);
>  			if (!dsi_device) {
>  				kfree(dsi_host);
> +				dsi_host = NULL;
>  				return -ENOMEM;
>  			}
>  		}
>  
>  		dsi_host->dev = dev;
> -		mipi_dsi_host_register(dsi_host);
> +		ret = mipi_dsi_host_register(dsi_host);
> +		if (ret) {
> +			DRM_ERROR("failed to register dsi host\n");
> +			kfree(dsi_device);
> +			dsi_device = NULL;
> +			kfree(dsi_host);
> +			dsi_host = NULL;
> +			return ret;
> +		}
> +
> +		host_registered = true;
>  	}
>  
>  	/* Find ADV7535 node and initialize it */
>  	dsi_out = of_graph_get_endpoint_by_regs(dev->of_node, 0, 1);
>  	if (!dsi_out) {
>  		DRM_ERROR("Failed to get dsi_out node info from DT\n");
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto err_unregister_host;
>  	}
>  	encoder_node = of_graph_get_remote_port_parent(dsi_out);
>  	if (!encoder_node) {
>  		of_node_put(dsi_out);
>  		DRM_ERROR("Failed to get bridge info from DT\n");
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto err_unregister_host;
>  	}
>  	/* Locate drm bridge from the hdmi encoder DT node */
>  	adv_bridge = of_drm_find_bridge(encoder_node);
> @@ -256,10 +282,16 @@ int kmb_dsi_host_bridge_init(struct device *dev)
>  	of_node_put(encoder_node);
>  	if (!adv_bridge) {
>  		DRM_DEBUG("Wait for external bridge driver DT\n");
> -		return -EPROBE_DEFER;
> +		ret = -EPROBE_DEFER;
> +		goto err_unregister_host;
>  	}
>  
>  	return 0;
> +
> +err_unregister_host:
> +	if (host_registered)
> +		kmb_dsi_host_unregister(NULL);
> +	return ret;
>  }
>  
>  static u32 mipi_get_datatype_params(u32 data_type, u32 data_mode,
> -- 
> 2.43.0
> 
ping.