[PATCHv2,2/2] gpio: mvebu: fix gpio bank registration when pwm is used

If more than one gpio bank has the "pwm" property, only one will be
registered successfully, all the others will fail with:
mvebu-gpio: probe of f1018140.gpio failed with error -17

That's because in alloc_pwms(), the chip->base (aka "int pwm"), was not
set (thus, ==0) ; and 0 is a meaningful start value in alloc_pwm().
What was intended is mvpwm->chip->base = -1.
Like that, the numbering will be done auto-magically

Moreover, as the region might be already occupied by another pwm, we
shouldn't force:
mvpwm->chip->base = 0
nor
mvpwm->chip->base = id * MVEBU_MAX_GPIO_PER_BANK;

Tested on clearfog-pro (Marvell 88F6828)

Fixes: 757642f9a584 ("gpio: mvebu: Add limited PWM support")
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
---
 drivers/gpio/gpio-mvebu.c | 7 +++++++
 1 file changed, 7 insertions(+)

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Hi Richard,
 
 On jeu., juin 01 2017, Richard Genoud <richard.genoud@gmail.com> wrote:

> If more than one gpio bank has the "pwm" property, only one will be
> registered successfully, all the others will fail with:
> mvebu-gpio: probe of f1018140.gpio failed with error -17
>
> That's because in alloc_pwms(), the chip->base (aka "int pwm"), was not
> set (thus, ==0) ; and 0 is a meaningful start value in alloc_pwm().
> What was intended is mvpwm->chip->base = -1.
> Like that, the numbering will be done auto-magically
>
> Moreover, as the region might be already occupied by another pwm, we
> shouldn't force:
> mvpwm->chip->base = 0
> nor
> mvpwm->chip->base = id * MVEBU_MAX_GPIO_PER_BANK;
>
> Tested on clearfog-pro (Marvell 88F6828)
>
> Fixes: 757642f9a584 ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Richard Genoud <richard.genoud@gmail.com>

Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

Thanks,

Gregory


> ---
>  drivers/gpio/gpio-mvebu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> index cdef2c78cb3b..5104b6398139 100644
> --- a/drivers/gpio/gpio-mvebu.c
> +++ b/drivers/gpio/gpio-mvebu.c
> @@ -768,6 +768,13 @@ static int mvebu_pwm_probe(struct platform_device *pdev,
>  	mvpwm->chip.dev = dev;
>  	mvpwm->chip.ops = &mvebu_pwm_ops;
>  	mvpwm->chip.npwm = mvchip->chip.ngpio;
> +	/*
> +	 * There may already be some PWM allocated, so we can't force
> +	 * mvpwm->chip.base to a fixed point like mvchip->chip.base.
> +	 * So, we let pwmchip_add() do the numbering and take the next free
> +	 * region.
> +	 */
> +	mvpwm->chip.base = -1;
>  
>  	spin_lock_init(&mvpwm->lock);
>

On Thu, Jun 1, 2017 at 2:18 PM, Richard Genoud <richard.genoud@gmail.com> wrote:

> If more than one gpio bank has the "pwm" property, only one will be
> registered successfully, all the others will fail with:
> mvebu-gpio: probe of f1018140.gpio failed with error -17
>
> That's because in alloc_pwms(), the chip->base (aka "int pwm"), was not
> set (thus, ==0) ; and 0 is a meaningful start value in alloc_pwm().
> What was intended is mvpwm->chip->base = -1.
> Like that, the numbering will be done auto-magically
>
> Moreover, as the region might be already occupied by another pwm, we
> shouldn't force:
> mvpwm->chip->base = 0
> nor
> mvpwm->chip->base = id * MVEBU_MAX_GPIO_PER_BANK;
>
> Tested on clearfog-pro (Marvell 88F6828)
>
> Fixes: 757642f9a584 ("gpio: mvebu: Add limited PWM support")
> Signed-off-by: Richard Genoud <richard.genoud@gmail.com>

Patch applied for fixes with Gregory's review tag.

Yours,
Linus Walleij
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