linux-kernel - Re: [PATCH 1/2] i2c-mux-gpio: test if the gpio can sleep

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Date:	Thu, 10 Oct 2013 10:46:41 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Ionut Nicu <ioan.nicu.ext@....com>
CC:	Peter Korsgaard <peter.korsgaard@...co.com>,
	Wolfram Sang <wsa@...-dreams.de>,
	Alexander Sverdlin <alexander.sverdlin@....com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] i2c-mux-gpio: test if the gpio can sleep

On 10/10/2013 10:39 AM, Ionut Nicu wrote:
> Some gpio chips may have get/set operations that
> can sleep. For this type of chips we must use the
> _cansleep() version of gpio_set_value.
> 
> Signed-off-by: Ionut Nicu <ioan.nicu.ext@....com>
> ---
>  drivers/i2c/muxes/i2c-mux-gpio.c |   11 ++++++++---
>  1 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
> index a764da7..b5f17ef 100644
> --- a/drivers/i2c/muxes/i2c-mux-gpio.c
> +++ b/drivers/i2c/muxes/i2c-mux-gpio.c
> @@ -27,11 +27,16 @@ struct gpiomux {
>  
>  static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
>  {
> +	unsigned gpio;
>  	int i;
>  
> -	for (i = 0; i < mux->data.n_gpios; i++)
> -		gpio_set_value(mux->gpio_base + mux->data.gpios[i],
> -			       val & (1 << i));
> +	for (i = 0; i < mux->data.n_gpios; i++) {
> +		gpio = mux->gpio_base + mux->data.gpios[i];
> +		if (gpio_cansleep(gpio))
> +			gpio_set_value_cansleep(gpio, val & (1 << i));
> +		else
> +			gpio_set_value(gpio, val & (1 << i));

The proper way to do this is just always use the _cansleep() version.
gpio_set_value() only works for chips which do not sleep,
gpio_set_value_cansleep() works for both those who do sleep and those who do
not.

> +	}
>  }
>  
>  static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
> 

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