Dear Bryan Wu,
> Hi Marek,
>
> I think your patch is right here. I was confused by the
> devm_pinctrl_get_select_default() which returns a pointer to pinctrl
> instant.
> But there is no code use that pinctrl. From the documentation and some
> examples in drivers/, it helps to set proper pin configuration for
> GPIO usage which depends on the DT setting and pinctrl maps. So we
> need setup such pinctrl maps in the right place, otherwise this API
> call will return error.
>
> Looks like we only use *pinctrl as a return value of
> devm_pinctrl_get_select_default() instead of a real handler for
> further pinctrl operation.
>
> I'm OK with this patch now and will apply it to my for-next branch.
Please wait with that, as if there's no pinctrl in the DT file, it'll also error
out. This will cause breakage, I'll send a V2.
> Add Stephen to this loop, since he introduce this API.
>
> Thanks,
> -Bryan
>
> On Mon, Aug 27, 2012 at 6:05 PM, Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
> > Dear Bryan Wu,
> >
> > [...]
> >
> >> >> Maybe I don't understand how to use this 'pinctrl' in this patch,
> >> >> since I didn't see any code to use that.
> >> >> Could you please post code to configure the pins in gpio-leds driver?
> >> >
> >> > It's not code that uses this, it's a DT property. But then, if the DT
> >> > property is not present, this fails ... so this patch is wrong. The
> >> > pinctrl is used by simply specifying the "pinctrl-names" and
> >> > "pinctrl-0" properties in the DT file.
> >>
> >> I know this. What I don't understand of this patch is "how to use
> >> 'struct pinctrl *pinctrl;' which you get from DT tree"?
> >> So if there is no such property in DT, it will return an error, I
> >> don't think this is necessary.
> >
> > Indeed, so the error should be converted into warning, correct?
> >
> >> And if there is a property in DT, the *pinctrl will point to some
> >> instant. but there is no code to use this instant to control any pins
> >> in leds-gpio driver.
> >
> > The way I understand it is that the devm_pinctrl_get_select_default()
> > call configures the pin multiplexing, therefore further operation with
> > the device is possible. In this case, the pins are multiplexed as GPIO.
> >
> >> And why we need this to control pins in leds-gpio
> >> driver, since we can use gpio generic API to do that?
> >
> > You mean the hog gpios? I guess that's indeed possible, but I expected
> > putting this under the leds-gpio would be more correct or maybe more
> > systematic. Am I wrong?
> >
> >> Thanks,
> >> -Bryan
> >>
> >> > But I wonder how to go about this.
> >> >
> >> >> -Bryan
> >> >>
> >> >> >> > Signed-off-by: Marek Vasut <marex@xxxxxxx>
> >> >> >> > Cc: Bryan Wu <bryan.wu@xxxxxxxxxxxxx>
> >> >> >> > Cc: Richard Purdie <rpurdie@xxxxxxxxx>
> >> >> >> > Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
> >> >> >> > Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
> >> >> >> > Cc: linux-leds@xxxxxxxxxxxxxxx
> >> >> >> > ---
> >> >> >> >
> >> >> >> > drivers/leds/leds-gpio.c | 6 ++++++
> >> >> >> > 1 file changed, 6 insertions(+)
> >> >> >> >
> >> >> >> > diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
> >> >> >> > index cde85ba..877d69e 100644
> >> >> >> > --- a/drivers/leds/leds-gpio.c
> >> >> >> > +++ b/drivers/leds/leds-gpio.c
> >> >> >> > @@ -20,6 +20,7 @@
> >> >> >> >
> >> >> >> > #include <linux/slab.h>
> >> >> >> > #include <linux/workqueue.h>
> >> >> >> > #include <linux/module.h>
> >> >> >> >
> >> >> >> > +#include <linux/pinctrl/consumer.h>
> >> >> >> >
> >> >> >> > struct gpio_led_data {
> >> >> >> >
> >> >> >> > struct led_classdev cdev;
> >> >> >> >
> >> >> >> > @@ -234,8 +235,13 @@ static int __devinit gpio_led_probe(struct
> >> >> >> > platform_device *pdev)
> >> >> >> >
> >> >> >> > {
> >> >> >> >
> >> >> >> > struct gpio_led_platform_data *pdata =
> >> >> >> > pdev->dev.platform_data; struct gpio_leds_priv *priv;
> >> >> >> >
> >> >> >> > + struct pinctrl *pinctrl;
> >> >> >> >
> >> >> >> > int i, ret = 0;
> >> >> >> >
> >> >> >> > + pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
> >> >> >> > + if (IS_ERR(pinctrl))
> >> >> >> > + return PTR_ERR(pinctrl);
> >> >> >> > +
> >> >> >> >
> >> >> >> > if (pdata && pdata->num_leds) {
> >> >> >> >
> >> >> >> > priv = devm_kzalloc(&pdev->dev,
> >> >> >> >
> >> >> >> > sizeof_gpio_leds_priv(pdata->num
> >> >> >> > _le ds) ,
> >> >> >> >
> >> >> >> > --
> >> >> >> > 1.7.10.4
> >> >> >
> >> >> > Best regards,
> >> >> > Marek Vasut
> >> >
> >> > Best regards,
> >> > Marek Vasut
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