Re: [PATCH] i2c: Mark instantiated device nodes with OF_POPULATE

[Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>]

On Thu, Jan 15, 2015 at 08:33:18PM +0200, Pantelis Antoniou wrote:
> Mark (and unmark) device nodes with the POPULATE flag as appropriate.
> This is required to avoid multi probing when using I2C and device
> overlays containing a mux.
> This patch is also more careful with the release of the adapter device
> which caused a deadlock with muxes, and does not break the build
> on !OF since the node flag accessors are not defined then.
> 
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> ---
>  drivers/i2c/i2c-core.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index 39d25a8..1d44e3a 100644
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -1122,6 +1122,10 @@ EXPORT_SYMBOL_GPL(i2c_new_device);
>   */
>  void i2c_unregister_device(struct i2c_client *client)
>  {
> +#if IS_ENABLED(CONFIG_OF_DYNAMIC)

Hi Pantelis,

I thought I read a note somewhere a couple of days ago suggesting that
CONFIG_OF_DYNAMIC would go away soon. Also, of_node_clear_flag is defined
in #ifdef CONFIG_OF, and AFAICS none of the other callers set OF_POPULATED
in the context of CONFIG_OF_DYNAMIC. Given that, wouldn't it be better
to use CONFIG_OF ?

Thanks,
Guenter

> +	if (client->dev.of_node)
> +		of_node_clear_flag(client->dev.of_node, OF_POPULATED);
> +#endif
>  	device_unregister(&client->dev);
>  }
>  EXPORT_SYMBOL_GPL(i2c_unregister_device);
> @@ -1441,8 +1445,11 @@ static void of_i2c_register_devices(struct i2c_adapter *adap)
>  
>  	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
>  
> -	for_each_available_child_of_node(adap->dev.of_node, node)
> +	for_each_available_child_of_node(adap->dev.of_node, node) {
> +		if (of_node_test_and_set_flag(node, OF_POPULATED))
> +			continue;
>  		of_i2c_register_device(adap, node);
> +	}
>  }
>  
>  static int of_dev_node_match(struct device *dev, void *data)
> @@ -1976,6 +1983,11 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
>  		if (adap == NULL)
>  			return NOTIFY_OK;	/* not for us */
>  
> +		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
> +			put_device(&adap->dev);
> +			return NOTIFY_OK;
> +		}
> +
>  		client = of_i2c_register_device(adap, rd->dn);
>  		put_device(&adap->dev);
>  
> @@ -1986,6 +1998,10 @@ static int of_i2c_notify(struct notifier_block *nb, unsigned long action,
>  		}
>  		break;
>  	case OF_RECONFIG_CHANGE_REMOVE:
> +		/* already depopulated? */
> +		if (!of_node_check_flag(rd->dn, OF_POPULATED))
> +			return NOTIFY_OK;
> +
>  		/* find our device by node */
>  		client = of_find_i2c_device_by_node(rd->dn);
>  		if (client == NULL)
> -- 
> 1.7.12
>