Re: [PATCH v3 1/2] nouveau/bl: Assign different names to interfaces

[Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>]

On Sun, Nov 13, 2016 at 08:57:06PM +0100, Pierre Moreau wrote:
> From: Pierre Moreau <pierre.morrow@free.fr>
> 
> Currently, every backlight interface created by Nouveau uses the same name,
> nv_backlight. This leads to a sysfs warning as it tries to create an already
> existing folder. This patch adds a incremented number to the name, but keeps
> the initial name as nv_backlight, to avoid possibly breaking userspace; the
> second interface will be named nv_backlight1, and so on.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86539
> 
> v2:
> * Switch to using ida for generating unique IDs, as suggested by Ilia Mirkin;
> * Allocate backlight name on the stack, as suggested by Ilia Mirkin;
> * Move `nouveau_get_backlight_name()` to avoid forward declaration, as
>   suggested by Ilia Mirkin;
> * Fix reference to bug report formatting, as reported by Nick Tenney.
> 
> v3:
> * Define a macro for the size of the backlight name, to avoid defining
>   it multiple times;
> * Use snprintf in place of sprintf.
> 
> Signed-off-by: Pierre Moreau <pierre.morrow@free.fr>
> ---
>  drivers/gpu/drm/nouveau/nouveau_backlight.c | 65 +++++++++++++++++++++++++++--
>  drivers/gpu/drm/nouveau/nouveau_display.h   | 10 +++++
>  drivers/gpu/drm/nouveau/nouveau_drm.c       |  2 +
>  drivers/gpu/drm/nouveau/nouveau_drv.h       |  1 +
>  4 files changed, 74 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
> index 5e2c568..0e69612 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
> @@ -31,11 +31,32 @@
>   */
>  
>  #include <linux/backlight.h>
> +#include <linux/idr.h>
>  
>  #include "nouveau_drv.h"
>  #include "nouveau_reg.h"
>  #include "nouveau_encoder.h"
>  
> +static struct ida bl_ida;
> +#define BL_NAME_SIZE 15 // 12 for name + 2 for digits + 1 for '\0'
> +
> +struct backlight_connector {
> +	struct list_head head;
> +	int id;
> +};
> +
> +static void
> +nouveau_get_backlight_name(char backlight_name[BL_NAME_SIZE], struct
> +		backlight_connector *connector)
> +{
> +	const int nb = ida_simple_get(&bl_ida, 0, 0, GFP_KERNEL);
> +	if (nb > 0 && nb < 100)
> +		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
> +	else
> +		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight");
> +	connector->id = nb;
> +}
> +

Just a minor issue, in the >= 100 case, backlight creation should probably
fail rather than reverting to "nv_backlight".  Other than that LGTM.

Thanks,

Lukas

>  static int
>  nv40_get_intensity(struct backlight_device *bd)
>  {
> @@ -74,6 +95,8 @@ nv40_backlight_init(struct drm_connector *connector)
>  	struct nvif_object *device = &drm->device.object;
>  	struct backlight_properties props;
>  	struct backlight_device *bd;
> +	struct backlight_connector bl_connector;
> +	char backlight_name[BL_NAME_SIZE];
>  
>  	if (!(nvif_rd32(device, NV40_PMC_BACKLIGHT) & NV40_PMC_BACKLIGHT_MASK))
>  		return 0;
> @@ -81,10 +104,16 @@ nv40_backlight_init(struct drm_connector *connector)
>  	memset(&props, 0, sizeof(struct backlight_properties));
>  	props.type = BACKLIGHT_RAW;
>  	props.max_brightness = 31;
> -	bd = backlight_device_register("nv_backlight", connector->kdev, drm,
> +	nouveau_get_backlight_name(backlight_name, &bl_connector);
> +	bd = backlight_device_register(backlight_name , connector->kdev, drm,
>  				       &nv40_bl_ops, &props);
> -	if (IS_ERR(bd))
> +
> +	if (IS_ERR(bd)) {
> +		if (bl_connector.id > 0)
> +			ida_simple_remove(&bl_ida, bl_connector.id);
>  		return PTR_ERR(bd);
> +	}
> +	list_add(&bl_connector.head, &drm->bl_connectors);
>  	drm->backlight = bd;
>  	bd->props.brightness = nv40_get_intensity(bd);
>  	backlight_update_status(bd);
> @@ -182,6 +211,8 @@ nv50_backlight_init(struct drm_connector *connector)
>  	struct backlight_properties props;
>  	struct backlight_device *bd;
>  	const struct backlight_ops *ops;
> +	struct backlight_connector bl_connector;
> +	char backlight_name[BL_NAME_SIZE];
>  
>  	nv_encoder = find_encoder(connector, DCB_OUTPUT_LVDS);
>  	if (!nv_encoder) {
> @@ -203,11 +234,17 @@ nv50_backlight_init(struct drm_connector *connector)
>  	memset(&props, 0, sizeof(struct backlight_properties));
>  	props.type = BACKLIGHT_RAW;
>  	props.max_brightness = 100;
> -	bd = backlight_device_register("nv_backlight", connector->kdev,
> +	nouveau_get_backlight_name(backlight_name, &bl_connector);
> +	bd = backlight_device_register(backlight_name , connector->kdev,
>  				       nv_encoder, ops, &props);
> -	if (IS_ERR(bd))
> +
> +	if (IS_ERR(bd)) {
> +		if (bl_connector.id > 0)
> +			ida_simple_remove(&bl_ida, bl_connector.id);
>  		return PTR_ERR(bd);
> +	}
>  
> +	list_add(&bl_connector.head, &drm->bl_connectors);
>  	drm->backlight = bd;
>  	bd->props.brightness = bd->ops->get_brightness(bd);
>  	backlight_update_status(bd);
> @@ -221,6 +258,8 @@ nouveau_backlight_init(struct drm_device *dev)
>  	struct nvif_device *device = &drm->device;
>  	struct drm_connector *connector;
>  
> +	INIT_LIST_HEAD(&drm->bl_connectors);
> +
>  	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
>  		if (connector->connector_type != DRM_MODE_CONNECTOR_LVDS &&
>  		    connector->connector_type != DRM_MODE_CONNECTOR_eDP)
> @@ -247,9 +286,27 @@ void
>  nouveau_backlight_exit(struct drm_device *dev)
>  {
>  	struct nouveau_drm *drm = nouveau_drm(dev);
> +	struct backlight_connector *connector;
> +
> +	list_for_each_entry(connector, &drm->bl_connectors, head) {
> +		if (connector->id >= 0)
> +			ida_simple_remove(&bl_ida, connector->id);
> +	}
>  
>  	if (drm->backlight) {
>  		backlight_device_unregister(drm->backlight);
>  		drm->backlight = NULL;
>  	}
>  }
> +
> +void
> +nouveau_backlight_ctor(void)
> +{
> +	ida_init(&bl_ida);
> +}
> +
> +void
> +nouveau_backlight_dtor(void)
> +{
> +	ida_destroy(&bl_ida);
> +}
> diff --git a/drivers/gpu/drm/nouveau/nouveau_display.h b/drivers/gpu/drm/nouveau/nouveau_display.h
> index 330fe0f..4a75df0 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_display.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_display.h
> @@ -91,6 +91,8 @@ int nouveau_crtc_set_config(struct drm_mode_set *set);
>  #ifdef CONFIG_DRM_NOUVEAU_BACKLIGHT
>  extern int nouveau_backlight_init(struct drm_device *);
>  extern void nouveau_backlight_exit(struct drm_device *);
> +extern void nouveau_backlight_ctor(void);
> +extern void nouveau_backlight_dtor(void);
>  #else
>  static inline int
>  nouveau_backlight_init(struct drm_device *dev)
> @@ -101,6 +103,14 @@ nouveau_backlight_init(struct drm_device *dev)
>  static inline void
>  nouveau_backlight_exit(struct drm_device *dev) {
>  }
> +
> +static inline void
> +nouveau_backlight_ctor(void) {
> +}
> +
> +static inline void
> +nouveau_backlight_dtor(void) {
> +}
>  #endif
>  
>  struct drm_framebuffer *
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
> index 9876e6f..2b93b55 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -1113,6 +1113,7 @@ nouveau_drm_init(void)
>  #endif
>  
>  	nouveau_register_dsm_handler();
> +	nouveau_backlight_ctor();
>  	return drm_pci_init(&driver_pci, &nouveau_drm_pci_driver);
>  }
>  
> @@ -1123,6 +1124,7 @@ nouveau_drm_exit(void)
>  		return;
>  
>  	drm_pci_exit(&driver_pci, &nouveau_drm_pci_driver);
> +	nouveau_backlight_dtor();
>  	nouveau_unregister_dsm_handler();
>  
>  #ifdef CONFIG_NOUVEAU_PLATFORM_DRIVER
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
> index 4cd47ba..923dbce 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drv.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
> @@ -161,6 +161,7 @@ struct nouveau_drm {
>  	struct nvbios vbios;
>  	struct nouveau_display *display;
>  	struct backlight_device *backlight;
> +	struct list_head bl_connectors;
>  
>  	/* power management */
>  	struct nouveau_hwmon *hwmon;
> -- 
> 2.10.2
> 
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