linux-kernel - Re: [PATCH 1/1] gpio: twl4030: Fix regression for twl gpio LED output

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Message-ID: <52A04442.6050607@ti.com>
Date:	Thu, 5 Dec 2013 11:15:46 +0200
From:	Roger Quadros <rogerq@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	<linus.walleij@...aro.org>, <peter.ujfalusi@...com>, <nm@...com>,
	<tomi.valkeinen@...com>, <balbi@...com>,
	<linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/1] gpio: twl4030: Fix regression for twl gpio LED output

On 12/04/2013 07:37 PM, Tony Lindgren wrote:
> * Roger Quadros <rogerq@...com> [131204 03:35]:
>> Commit 0b2aa8be introduced a regression that causes failure
>> in setting LED GPO direction to OUT.
>>
>> This causes USB host probe failures for Beagleboard C4.
>>
>> [    2.075469] platform usb_phy_gen_xceiv.2: Driver usb_phy_gen_xceiv requests probe deferral
>> [    2.090454] hsusb2_vcc: Failed to request enable GPIO510: -22
>> [    2.100982] reg-fixed-voltage reg-fixed-voltage.0.auto: Failed to register regulator: -22
>> [    2.109954] reg-fixed-voltage: probe of reg-fixed-voltage.0.auto failed with error -22
>>
>> direction_out/direction_in must return 0 if the operation succeeded.
> 
> Uh, OK, sorry that was an unexpected side effect. We still should keep the
> return values though instead of just ignoring them.

OK.
>  
>>  1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-twl4030.c b/drivers/gpio/gpio-twl4030.c
>> index b97d6a6..0999ed1 100644
>> --- a/drivers/gpio/gpio-twl4030.c
>> +++ b/drivers/gpio/gpio-twl4030.c
>> @@ -294,13 +294,13 @@ out:
>>  static int twl_direction_in(struct gpio_chip *chip, unsigned offset)
>>  {
>>  	struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
>> -	int ret;
>> +	int ret = 0;
>>  
>>  	mutex_lock(&priv->mutex);
>>  	if (offset < TWL4030_GPIO_MAX)
>> -		ret = twl4030_set_gpio_direction(offset, 1);
>> +		twl4030_set_gpio_direction(offset, 1);
>>  	else
>> -		ret = -EINVAL;
>> +		ret = -EINVAL;	/* LED outputs can't be set as input */
>>  
>>  	if (!ret)
>>  		priv->direction &= ~BIT(offset);
> 
> This looks OK to me.
> 
>> @@ -354,18 +354,21 @@ static void twl_set(struct gpio_chip *chip, unsigned offset, int value)
>>  static int twl_direction_out(struct gpio_chip *chip, unsigned offset, int value)
>>  {
>>  	struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
>> -	int ret = -EINVAL;
>>  
> 
> Can't you just have:
> 
> 	int ret = 0;

Yes, i'll add that.
> 
>>  	mutex_lock(&priv->mutex);
>>  	if (offset < TWL4030_GPIO_MAX)
>> -		ret = twl4030_set_gpio_direction(offset, 0);
>> +		twl4030_set_gpio_direction(offset, 0);
>> +
>> +	/*
>> +	 *  LED gpio's i.e. offset >= TWL4030_GPIO_MAX are always output
>> +	 */
>>  
>>  	priv->direction |= BIT(offset);
>>  	mutex_unlock(&priv->mutex);
>>  
>>  	twl_set(chip, offset, value);
>>  
>> -	return ret;
>> +	return 0;
>>  }
> 
> Then the rest of this change is not needed and we check the return value for
> twl4030_set_gpio_direction. Makes sense to keep the comment there though.

OK. Will post v2.

cheers,
-roger

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