Re: [PATCH v8 2/2] drm/debugfs: add top-level 'bridges' file showing all added bridges

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 26 Feb 2025, Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
> The global bridges_list holding all the bridges between drm_bridge_add()
> and drm_bridge_remove() cannot be inspected via debugfs. Add a file showing
> it.
>
> To avoid code duplication, move the code printing a bridge info to a common
> function.

Going forward, please separate refactoring (extracting the function)
from the functional changes (adding the new debugfs) to independent
patches. It's just easier to review.

Anyway, I reviewed this one, so no need to roll another version.

And thanks for doing this; I believe the end result is better.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
>
> ---
>
> Changed in v8:
> - add the file in drm_bridge.c, which avois the added #if CONFIG_DEBUG_FS
> - fix incorrect (but harmless) idx increment in
>   drm_bridge_debugfs_show_bridge()
>
> Changed in v7:
> - move implementation to drm_bridge.c to avoid exporting bridge_list and
>   bridge_mutex
>
> This patch was added in v6.
> ---
>  drivers/gpu/drm/drm_bridge.c | 72 ++++++++++++++++++++++++++++++--------------
>  drivers/gpu/drm/drm_drv.c    |  2 ++
>  include/drm/drm_bridge.h     |  1 +
>  3 files changed, 53 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index a6bf1a565e3c3a8d24de60448972849f6d86ba72..9c6e35d41ed54a14d5745e684a341c907ed84d6b 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -1336,6 +1336,49 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
>  EXPORT_SYMBOL(of_drm_find_bridge);
>  #endif
>  
> +static void drm_bridge_debugfs_show_bridge(struct drm_printer *p,
> +					   struct drm_bridge *bridge,
> +					   unsigned int idx)
> +{
> +	drm_printf(p, "bridge[%u]: %ps\n", idx, bridge->funcs);
> +	drm_printf(p, "\ttype: [%d] %s\n",
> +		   bridge->type,
> +		   drm_get_connector_type_name(bridge->type));
> +
> +	if (bridge->of_node)
> +		drm_printf(p, "\tOF: %pOFfc\n", bridge->of_node);
> +
> +	drm_printf(p, "\tops: [0x%x]", bridge->ops);
> +	if (bridge->ops & DRM_BRIDGE_OP_DETECT)
> +		drm_puts(p, " detect");
> +	if (bridge->ops & DRM_BRIDGE_OP_EDID)
> +		drm_puts(p, " edid");
> +	if (bridge->ops & DRM_BRIDGE_OP_HPD)
> +		drm_puts(p, " hpd");
> +	if (bridge->ops & DRM_BRIDGE_OP_MODES)
> +		drm_puts(p, " modes");
> +	if (bridge->ops & DRM_BRIDGE_OP_HDMI)
> +		drm_puts(p, " hdmi");
> +	drm_puts(p, "\n");
> +}
> +
> +static int allbridges_show(struct seq_file *m, void *data)
> +{
> +	struct drm_printer p = drm_seq_file_printer(m);
> +	struct drm_bridge *bridge;
> +	unsigned int idx = 0;
> +
> +	mutex_lock(&bridge_lock);
> +
> +	list_for_each_entry(bridge, &bridge_list, list)
> +		drm_bridge_debugfs_show_bridge(&p, bridge, idx++);
> +
> +	mutex_unlock(&bridge_lock);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(allbridges);
> +
>  static int encoder_bridges_show(struct seq_file *m, void *data)
>  {
>  	struct drm_encoder *encoder = m->private;
> @@ -1343,33 +1386,18 @@ static int encoder_bridges_show(struct seq_file *m, void *data)
>  	struct drm_bridge *bridge;
>  	unsigned int idx = 0;
>  
> -	drm_for_each_bridge_in_chain(encoder, bridge) {
> -		drm_printf(&p, "bridge[%u]: %ps\n", idx++, bridge->funcs);
> -		drm_printf(&p, "\ttype: [%d] %s\n",
> -			   bridge->type,
> -			   drm_get_connector_type_name(bridge->type));
> -
> -		if (bridge->of_node)
> -			drm_printf(&p, "\tOF: %pOFfc\n", bridge->of_node);
> -
> -		drm_printf(&p, "\tops: [0x%x]", bridge->ops);
> -		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
> -			drm_puts(&p, " detect");
> -		if (bridge->ops & DRM_BRIDGE_OP_EDID)
> -			drm_puts(&p, " edid");
> -		if (bridge->ops & DRM_BRIDGE_OP_HPD)
> -			drm_puts(&p, " hpd");
> -		if (bridge->ops & DRM_BRIDGE_OP_MODES)
> -			drm_puts(&p, " modes");
> -		if (bridge->ops & DRM_BRIDGE_OP_HDMI)
> -			drm_puts(&p, " hdmi");
> -		drm_puts(&p, "\n");
> -	}
> +	drm_for_each_bridge_in_chain(encoder, bridge)
> +		drm_bridge_debugfs_show_bridge(&p, bridge, idx++);
>  
>  	return 0;
>  }
>  DEFINE_SHOW_ATTRIBUTE(encoder_bridges);
>  
> +void drm_bridge_debugfs_params(struct dentry *root)
> +{
> +	debugfs_create_file("bridges", 0444, root, NULL, &allbridges_fops);
> +}
> +
>  void drm_bridge_debugfs_encoder_params(struct dentry *root,
>  				       struct drm_encoder *encoder)
>  {
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 3cf440eee8a2ab3de134d925db8f1d2ce68062b7..22e8cd0a6a37a0ac25535e9d570da25571b0b2bc 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -38,6 +38,7 @@
>  #include <linux/xarray.h>
>  
>  #include <drm/drm_accel.h>
> +#include <drm/drm_bridge.h>
>  #include <drm/drm_cache.h>
>  #include <drm/drm_client_event.h>
>  #include <drm/drm_color_mgmt.h>
> @@ -1120,6 +1121,7 @@ static int __init drm_core_init(void)
>  	}
>  
>  	drm_debugfs_root = debugfs_create_dir("dri", NULL);
> +	drm_bridge_debugfs_params(drm_debugfs_root);
>  
>  	ret = register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops);
>  	if (ret < 0)
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index 0890acfe04b99b1ccbbff10b507cb8c2b2705e06..2a99d70865571f24db0ca75c758cfd09d3a5d459 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -1108,6 +1108,7 @@ static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
>  }
>  #endif
>  
> +void drm_bridge_debugfs_params(struct dentry *root);
>  void drm_bridge_debugfs_encoder_params(struct dentry *root, struct drm_encoder *encoder);
>  
>  #endif

-- 
Jani Nikula, Intel