Re: [RFC PATCH 3/4] i2c: core: treat EPROBE_DEFER when acquiring SCL/SDA GPIOs

From: Wolfram Sang <wsa@kernel.org>
To: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Cc: linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, robh+dt@kernel.org,
	ludovic.desroches@microchip.com, nicolas.ferre@microchip.com,
	alexandre.belloni@bootlin.com, linux@armlinux.org.uk,
	kamel.bouhara@bootlin.com
Subject: Re: [RFC PATCH 3/4] i2c: core: treat EPROBE_DEFER when acquiring SCL/SDA GPIOs
Date: Sun, 2 Aug 2020 19:05:00 +0200	[thread overview]
Message-ID: <20200802170500.GB10193@kunai> (raw)
In-Reply-To: <20200619141904.910889-4-codrin.ciubotariu@microchip.com>

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On Fri, Jun 19, 2020 at 05:19:03PM +0300, Codrin Ciubotariu wrote:
> Even if I2C bus GPIO recovery is optional, devm_gpiod_get() can return
> -EPROBE_DEFER, so we should at least treat that. This ends up with
> i2c_register_adapter() to be able to return -EPROBE_DEFER.
> 
> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
> ---
>  drivers/i2c/i2c-core-base.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 4ee29fec4e93..f8d9f2048ca8 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -368,15 +368,16 @@ static int i2c_gpio_init_recovery(struct i2c_adapter *adap)
>  	return i2c_gpio_init_generic_recovery(adap);
>  }
>  
> -static void i2c_init_recovery(struct i2c_adapter *adap)
> +static int i2c_init_recovery(struct i2c_adapter *adap)
>  {
>  	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
>  	char *err_str;
>  
>  	if (!bri)
> -		return;
> +		return 0;
>  
> -	i2c_gpio_init_recovery(adap);
> +	if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER)
> +		return -EPROBE_DEFER;
>  
>  	if (!bri->recover_bus) {
>  		err_str = "no recover_bus() found";
> @@ -392,7 +393,7 @@ static void i2c_init_recovery(struct i2c_adapter *adap)
>  			if (gpiod_get_direction(bri->sda_gpiod) == 0)
>  				bri->set_sda = set_sda_gpio_value;
>  		}
> -		return;
> +		return 0;

This is correct but I think the code flow is/was confusing. Can you drop
this 'return' and use 'else if' for the next code block? I think this is
more readable.

>  	}
>  
>  	if (bri->recover_bus == i2c_generic_scl_recovery) {
> @@ -407,10 +408,12 @@ static void i2c_init_recovery(struct i2c_adapter *adap)
>  		}
>  	}
>  
> -	return;
> +	return 0;
>   err:
>  	dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
>  	adap->bus_recovery_info = NULL;
> +
> +	return 0;

'return -EINVAL;' I'd suggest.

>  }
>  
>  static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
> @@ -1476,7 +1479,9 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
>  			 "Failed to create compatibility class link\n");
>  #endif
>  
> -	i2c_init_recovery(adap);
> +	res = i2c_init_recovery(adap);
> +	if (res == -EPROBE_DEFER)
> +		goto out_link;

Please move 'i2c_init_recovery' above the class-link creation. It
shouldn't make a difference but we can skip the extra label and the
ifdeffery.

>  
>  	/* create pre-declared device nodes */
>  	of_i2c_register_devices(adap);
> @@ -1493,6 +1498,11 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
>  
>  	return 0;
>  
> +out_link:
> +#ifdef CONFIG_I2C_COMPAT
> +	class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
> +				 adap->dev.parent);
> +#endif
>  out_reg:
>  	init_completion(&adap->dev_released);
>  	device_unregister(&adap->dev);
> -- 
> 2.25.1
> 

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