Re: [PATCH v2] pinctrl: qcom: support gpio_chip .set_config call

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Wed 03 Mar 07:18 CST 2021, Shawn Guo wrote:

> In case of ACPI boot, GPIO core does the right thing to parse GPIO pin
> configs from ACPI table, and call into gpio_chip's .set_config hook for
> setting them up.  It enables such support on qcom platform by using
> generic config function, which in turn calls into .pin_config_set of
> pinconf for setting up hardware.  For qcom platform, it's possible to
> reuse pin group config functions for pin config hooks, because every pin
> is maintained as a single group.
> 
> This change fixes the problem that Touchpad of Lenovo Flex 5G laptop
> doesn't work with ACPI boot, because PullUp config of Touchpad GpioInt
> pin is not set up by the kernel.
> 

I like the fact that this solves your gpio configuration issue, but I'm
uncertain if just adding support for configuring pins (in addition to
groups) in the driver is the right solution.

@Linus, to summarize, the Qualcomm TLMM configures pingroups, but all
gpios are defined as a single pin. pinctrl_gpio_set_config() is invoked
based on the configuration provided in the ACPI tables, so Shawn's
proposal is to just implement "config by pin" as well.
Would this not be a problem shared with all pinctrl drivers that
configure gpios in groups?

> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> ---
> Changes for v2:
> - Add pin config functions that simply call into group config ones.
> 
>  drivers/pinctrl/qcom/pinctrl-msm.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
> index af6ed7f43058..a59bb4cbd97e 100644
> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
> @@ -489,10 +489,24 @@ static int msm_config_group_set(struct pinctrl_dev *pctldev,
>  	return 0;
>  }
>  
> +static int msm_config_pin_get(struct pinctrl_dev *pctldev, unsigned int pin,
> +			      unsigned long *config)
> +{
> +	return msm_config_group_get(pctldev, pin, config);
> +}
> +
> +static int msm_config_pin_set(struct pinctrl_dev *pctldev, unsigned pin,
> +			      unsigned long *configs, unsigned num_configs)
> +{
> +	return msm_config_group_set(pctldev, pin, configs, num_configs);
> +}
> +
>  static const struct pinconf_ops msm_pinconf_ops = {
>  	.is_generic		= true,
>  	.pin_config_group_get	= msm_config_group_get,
>  	.pin_config_group_set	= msm_config_group_set,
> +	.pin_config_get		= msm_config_pin_get,
> +	.pin_config_set		= msm_config_pin_set,
>  };
>  
>  static int msm_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> @@ -717,6 +731,7 @@ static const struct gpio_chip msm_gpio_template = {
>  	.get_direction    = msm_gpio_get_direction,
>  	.get              = msm_gpio_get,
>  	.set              = msm_gpio_set,
> +	.set_config       = gpiochip_generic_config,

Generally the pinconf/pinmux part of the driver deals with groups, and
the gpio_chip deals with gpio numbers. So I think that either
gpiochip_generic_config() should somehow do the translation, or we
should use a different function that does it (even though there's no
translation).

Regards,
Bjorn

>  	.request          = gpiochip_generic_request,
>  	.free             = gpiochip_generic_free,
>  	.dbg_show         = msm_gpio_dbg_show,
> -- 
> 2.17.1
>