[PATCH 4/8] ARM: at91: do not configure at91sam9g10 twi pio as open-drain

[Warner Losh]

On Aug 31, 2012, at 3:21 AM, <ludovic.desroches at atmel.com> <ludovic.desroches at atmel.com> wrote:

> From: Ludovic Desroches <ludovic.desroches at atmel.com>
> 
> As indicated in the datasheet, TWD and TWCK must not be programmed as
> open-drain.
> 
> Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
> ---
> arch/arm/mach-at91/at91sam9261_devices.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm/mach-at91/at91sam9261_devices.c b/arch/arm/mach-at91/at91sam9261_devices.c
> index c94495d..405f603 100644
> --- a/arch/arm/mach-at91/at91sam9261_devices.c
> +++ b/arch/arm/mach-at91/at91sam9261_devices.c
> @@ -324,20 +324,22 @@ static struct platform_device at91sam9261_twi_device = {
> 
> void __init at91_add_device_i2c(struct i2c_board_info *devices, int nr_devices)
> {
> -	/* IP version is not the same on 9261 and g10 */
> +	/*
> +	 * IP version is not the same on 9261 and g10 and only 9261 one
> +	 * requires to configure PIO as open-drain.

"The IP version is not the same on the 9261 and g10.  Only the 9261
 requires PIO configured as open-drain."

would be a better way to say this.

> +	 */
> 	if (cpu_is_at91sam9g10()) {
> 		at91sam9261_twi_device.name = "at91sam9g10_i2c";
> +		at91_set_A_periph(AT91_PIN_PA7, 0);		/* TWD */
> +		at91_set_A_periph(AT91_PIN_PA8, 0);		/* TWCK */
> 	} else {
> 		at91sam9261_twi_device.name = "at91sam9261_i2c";
> +		at91_set_A_periph(AT91_PIN_PA7, 0);		/* TWD */
> +		at91_set_multi_drive(AT91_PIN_PA7, 1);
> +		at91_set_A_periph(AT91_PIN_PA8, 0);		/* TWCK */
> +		at91_set_multi_drive(AT91_PIN_PA8, 1);
> 	}
> 
> -	/* pins used for TWI interface */
> -	at91_set_A_periph(AT91_PIN_PA7, 0);		/* TWD */
> -	at91_set_multi_drive(AT91_PIN_PA7, 1);
> -
> -	at91_set_A_periph(AT91_PIN_PA8, 0);		/* TWCK */
> -	at91_set_multi_drive(AT91_PIN_PA8, 1);
> -

You could just move the two multi-drive lines up into the 9261 branch of the above if.  That would make it clearer that it is a workaround just for the 9261.

> 	i2c_register_board_info(0, devices, nr_devices);
> 	platform_device_register(&at91sam9261_twi_device);
> }
> -- 
> 1.7.11.3
> 
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