Re: GPIO request failure with PCF pinmux

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Friday 14 September 2012 22:11:00 Laurent Pinchart wrote:
> Hi Paul,
> 
> I ran into an issue with GPIO and pinmuxing in the TPU PWM driver.
> 
> The driver needs to switch the PWM pin between GPIO and function at runtime.
> To do so, I use the PWM pin GPIO (GPIO_PORT202) and the associated function
> GPIO (GPIO_FN_TPU0TO2_PORT202).
> 
> The driver configures the pin as a GPIO output when loaded with
> 
> 	gpio_request_one(GPIO_PORT202, GPIOF_INIT_LOW);
> 
> This results in a call to sh_pfc_gpio_request_enable() followed by a call to
> sh_pfc_reconfig_pin() for GPIO 202. The later changes the pinmux type from
> PINMUX_TYPE_GPIO (2) to PINMUX_TYPE_OUTPUT (3).
> 
> I then call gpio_free(GPIO_PORT202) and
> gpio_request(GPIO_FN_TPU0TO2_PORT202) to switch from GPIO to function. The
> former calls sh_pfc_gpio_disable_free:() on GPIO 202.
> 
> When I later call gpio_free(GPIO_FN_TPU0TO2_PORT202) and
> gpio_request_one(GPIO_PORT202, GPIOF_INIT_LOW), the call to
> sh_pfc_gpio_request_enable() fails with
> 
> pinctrl-sh_pfc pinctrl: Unsupported mux type (3), bailing...
> pinctrl-sh_pfc pinctrl-sh_pfc: request() failed for pin 202
> pinctrl-sh_pfc pinctrl-sh_pfc: pin-202 (pinctrl-sh_pfc) status -524
> 
> You're more familiar with pinmux than I am. Am I doing something wrong, or
> is there a bug in the PFC pinmux implementation ?

And while I'm at it, trying to set the pin to the PWM function doesn't seem to 
work anymore on v3.6. It looks like the pin stays configured as a GPIO. How am 
I supposed to configure pinmuxing from the driver ? Documentation/pinctrl.txt 
doesn't help much, and the code isn't easy to understand. There's probably no 
registered mapping (whatever a mapping is), are they supposed to come from DT 
?

-- 
Regards,

Laurent Pinchart