Re: [PATCH] drm/bridge: ti-sn65dsi86: Fix multiple instances

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Geert,

Thank you for the patch.

On Fri, Oct 18, 2024 at 09:45:52AM +0200, Geert Uytterhoeven wrote:
> Each bridge instance creates up to four auxiliary devices with different
> names.  However, their IDs are always zero, causing duplicate filename
> errors when a system has multiple bridges:
> 
>     sysfs: cannot create duplicate filename '/bus/auxiliary/devices/ti_sn65dsi86.gpio.0'
> 
> Fix this by using a unique instance ID per bridge instance.

Isn't this something that should be handled by the AUX core ? The code
below would otherwise need to be duplicated by all drivers, which seems
a burden we should avoid.

> Fixes: bf73537f411b0d4f ("drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> /sys/bus/auxiliary/devices
> ├── ti_sn65dsi86.gpio.0
> ├── ti_sn65dsi86.pwm.0
> ├── ti_sn65dsi86.aux.0
> ├── ti_sn65dsi86.bridge.0
> ├── ti_sn65dsi86.gpio.1
> ├── ti_sn65dsi86.pwm.1
> ├── ti_sn65dsi86.aux.1
> └── ti_sn65dsi86.bridge.1
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 9e31f750fd889745..8f6ac48aefdb70b3 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -13,6 +13,7 @@
>  #include <linux/gpio/consumer.h>
>  #include <linux/gpio/driver.h>
>  #include <linux/i2c.h>
> +#include <linux/idr.h>
>  #include <linux/iopoll.h>
>  #include <linux/module.h>
>  #include <linux/of_graph.h>
> @@ -168,6 +169,7 @@
>   * @pwm_enabled:  Used to track if the PWM signal is currently enabled.
>   * @pwm_pin_busy: Track if GPIO4 is currently requested for GPIO or PWM.
>   * @pwm_refclk_freq: Cache for the reference clock input to the PWM.
> + * @id:           Unique instance ID
>   */
>  struct ti_sn65dsi86 {
>  	struct auxiliary_device		*bridge_aux;
> @@ -202,8 +204,11 @@ struct ti_sn65dsi86 {
>  	atomic_t			pwm_pin_busy;
>  #endif
>  	unsigned int			pwm_refclk_freq;
> +	int				id;
>  };
>  
> +static DEFINE_IDA(ti_sn65dsi86_ida);
> +
>  static const struct regmap_range ti_sn65dsi86_volatile_ranges[] = {
>  	{ .range_min = 0, .range_max = 0xFF },
>  };
> @@ -488,6 +493,7 @@ static int ti_sn65dsi86_add_aux_device(struct ti_sn65dsi86 *pdata,
>  		return -ENOMEM;
>  
>  	aux->name = name;
> +	aux->id = pdata->id;
>  	aux->dev.parent = dev;
>  	aux->dev.release = ti_sn65dsi86_aux_device_release;
>  	device_set_of_node_from_dev(&aux->dev, dev);
> @@ -1889,6 +1895,13 @@ static int ti_sn65dsi86_parse_regulators(struct ti_sn65dsi86 *pdata)
>  				       pdata->supplies);
>  }
>  
> +static void ti_sn65dsi86_devm_ida_free(void *data)
> +{
> +	struct ti_sn65dsi86 *pdata = data;
> +
> +	ida_free(&ti_sn65dsi86_ida, pdata->id);
> +}
> +
>  static int ti_sn65dsi86_probe(struct i2c_client *client)
>  {
>  	struct device *dev = &client->dev;
> @@ -1903,6 +1916,17 @@ static int ti_sn65dsi86_probe(struct i2c_client *client)
>  	pdata = devm_kzalloc(dev, sizeof(struct ti_sn65dsi86), GFP_KERNEL);
>  	if (!pdata)
>  		return -ENOMEM;
> +
> +	ret = ida_alloc(&ti_sn65dsi86_ida, GFP_KERNEL);
> +	if (ret < 0)
> +		return ret;
> +
> +	pdata->id = ret;
> +
> +	ret = devm_add_action_or_reset(dev, ti_sn65dsi86_devm_ida_free, pdata);
> +	if (ret)
> +		return ret;
> +
>  	dev_set_drvdata(dev, pdata);
>  	pdata->dev = dev;
>  

-- 
Regards,

Laurent Pinchart