linux-kernel - Re: gpio-mcp23s08: i2c: auto-select base if no DT match or platform data

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Message-Id: <201307291110.19990.poeschel@lemonage.de>
Date:	Mon, 29 Jul 2013 11:10:19 +0200
From:	Lars Poeschel <poeschel@...onage.de>
To:	"Daniel M. Weeks" <dan@...weeks.net>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-kernel@...r.kernel.org
Subject: Re: gpio-mcp23s08: i2c: auto-select base if no DT match or platform data

On Friday 19 July 2013 at 06:19:58, Daniel M. Weeks wrote:
> The call to gpiochip_add made by this driver is capable of
> auto-selecting a base if one is not provided. However, it was not
> called unless there was already a DT entry or platform data. This patch
> calls it even if the base is not already known so that gpiochip_add can
> attempt to find a usable base.

Nitpick:
You describe what your patch changes in the commit message. This is good, 
but I can see the changes looking at the code. Can you please add a few 
lines describing WHY your patch is needed ? (That'd be to be able to 
instantiate a device from userspace with sysfs, right ?)

The code is ok, so with a modified commit message feel free to add my

Acked-by: Lars Poeschel <poeschel@...onage.de>

> Signed-off-by: Daniel M. Weeks <dan@...weeks.net>
> 
> ---
> drivers/gpio/gpio-mcp23s08.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-mcp23s08.c b/drivers/gpio/gpio-mcp23s08.c
> index 6a4470b..87ed6bf 100644
> --- a/drivers/gpio/gpio-mcp23s08.c
> +++ b/drivers/gpio/gpio-mcp23s08.c
> @@ -520,14 +520,13 @@ static int mcp230xx_probe(struct i2c_client
> *client,
> 
>  	match = of_match_device(of_match_ptr(mcp23s08_i2c_of_match),
>  					&client->dev);
> -	if (match) {
> +	pdata = client->dev.platform_data;
> +	if (match || !pdata) {
>  		base = -1;
>  		pullups = 0;
>  	} else {
> -		pdata = client->dev.platform_data;
> -		if (!pdata || !gpio_is_valid(pdata->base)) {
> -			dev_dbg(&client->dev,
> -					"invalid or missing platform data\n");
> +		if (!gpio_is_valid(pdata->base)) {
> +			dev_dbg(&client->dev, "invalid platform data\n");
>  			return -EINVAL;
>  		}
>  		base = pdata->base;

Thanks,
Lars

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