linux-kernel - Re: [PATCH] mfd: tps65010: fix init when the driver is built-in

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Message-ID: <20160111054948.GJ3331@x1>
Date:	Mon, 11 Jan 2016 05:49:48 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	Aaro Koskinen <aaro.koskinen@....fi>
Cc:	Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH] mfd: tps65010: fix init when the driver is built-in

On Fri, 08 Jan 2016, Aaro Koskinen wrote:

> tps65010 driver's initcall cannot succeed when the driver is built-in,
> because it expects that the I2C probe is completed at initcall time;
> this cannot happen as MFD is initialized before I2C. Also on systems
> where the chip is not present there is unnecessary 30 ms delay during
> the boot.
> 
> Instead of waiting for probe to finish, just register the I2C device.
> If some boards need retry mechanism for startup glitches, that should be
> done in the actual probe function. Also move the driver banner message
> to the probe function, and make it print the chip model being probed.
> 
> The patch allows to use tps65010 again with OMAP1 (where it's required
> to be built-in) and enables e.g. USB and LED functionality on OMAP5912 OSK.
> 
> Signed-off-by: Aaro Koskinen <aaro.koskinen@....fi>
> ---
>  drivers/mfd/tps65010.c | 23 +++--------------------
>  1 file changed, 3 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/mfd/tps65010.c b/drivers/mfd/tps65010.c
> index 448f0a1..450c358 100644
> --- a/drivers/mfd/tps65010.c
> +++ b/drivers/mfd/tps65010.c
> @@ -541,6 +541,8 @@ static int tps65010_probe(struct i2c_client *client,
>  	int			status;
>  	struct tps65010_board	*board = dev_get_platdata(&client->dev);
>  
> +	pr_info("%s: chip model %s\n", DRIVER_NAME, id->name);
> +

Why are you hand-rolling your own prints?  Use dev_*() instead.

Besides, this print looks pretty useless, so best to omit it
completely.

>  	if (the_tps) {
>  		dev_dbg(&client->dev, "only one tps6501x chip allowed\n");
>  		return -ENODEV;
> @@ -1059,26 +1061,7 @@ EXPORT_SYMBOL(tps65013_set_low_pwr);
>  
>  static int __init tps_init(void)
>  {
> -	u32	tries = 3;
> -	int	status = -ENODEV;
> -
> -	printk(KERN_INFO "%s: version %s\n", DRIVER_NAME, DRIVER_VERSION);
> -
> -	/* some boards have startup glitches */
> -	while (tries--) {
> -		status = i2c_add_driver(&tps65010_driver);
> -		if (the_tps)
> -			break;
> -		i2c_del_driver(&tps65010_driver);
> -		if (!tries) {
> -			printk(KERN_ERR "%s: no chip?\n", DRIVER_NAME);
> -			return -ENODEV;
> -		}
> -		pr_debug("%s: re-probe ...\n", DRIVER_NAME);
> -		msleep(10);
> -	}
> -
> -	return status;
> +	return i2c_add_driver(&tps65010_driver);
>  }
>  /* NOTE:  this MUST be initialized before the other parts of the system
>   * that rely on it ... but after the i2c bus on which this relies.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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