pinctrl: baytrail: show output gpio state correctly on Intel Baytrail
diff mbox

Message ID 20141013193618.GD29810@saruman
State Not Applicable
Headers show

Commit Message

Felipe Balbi Oct. 13, 2014, 7:36 p.m. UTC
On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote:
> Hi,
> 
> On Mon, Oct 13, 2014 at 12:24:04PM -0700, David Cohen wrote:
> > On Mon, Oct 13, 2014 at 02:14:05PM -0500, Felipe Balbi wrote:
> > > On Mon, Oct 13, 2014 at 11:23:59AM -0700, David Cohen wrote:
> > > > Even if a gpio pin is set to output, we still need to set INPUT_EN bit
> > > 
> > > here you say you're setting that bit.
> > > 
> > > > to be able to read its value. Without this change, we'll always read low
> > > > level state.
> > > > 
> > > > Cc: <stable@vger.kernel.org> # v3.14+
> > > > Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
> > > > ---
> > > > 
> > > > Hi,
> > > > 
> > > > I'm resending same v1 patch but now copying linux stable and linux gpio.
> > > > This patch is meant for all linux stable trees >= v3.14.
> > > > 
> > > > Br, David
> > > > ---
> > > > 
> > > >  drivers/pinctrl/pinctrl-baytrail.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> > > > index e12e5b07f6d7..c23d8ded936d 100644
> > > > --- a/drivers/pinctrl/pinctrl-baytrail.c
> > > > +++ b/drivers/pinctrl/pinctrl-baytrail.c
> > > > @@ -318,7 +318,7 @@ static int byt_gpio_direction_output(struct gpio_chip *chip,
> > > >  		"Potential Error: Setting GPIO with direct_irq_en to output");
> > > >  
> > > >  	reg_val = readl(reg) | BYT_DIR_MASK;
> > > > -	reg_val &= ~BYT_OUTPUT_EN;
> > > > +	reg_val &= ~(BYT_OUTPUT_EN | BYT_INPUT_EN);
> > > 
> > > but code is clearing it. Also, you're not patching byt_gpio_get(), so
> > > you can't be 'reading its value' either. Quite frankly, this looks very
> > > fishy to me. Comments on BYT_OUTPUT_EN and BYT_INPUT_EN states that
> > > those bits are active low, meaning that clearing them enables that
> > > particular feature.
> > > 
> > > How can you enable a pin to be both OUTPUT and INPUT ? Look like what
> > > you really want is:
> > > 
> > > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> > > index e12e5b0..69f882d 100644
> > > --- a/drivers/pinctrl/pinctrl-baytrail.c
> > > +++ b/drivers/pinctrl/pinctrl-baytrail.c
> > > @@ -290,6 +290,7 @@ static int byt_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> > >  
> > >  	value = readl(reg) | BYT_DIR_MASK;
> > >  	value &= ~BYT_INPUT_EN;		/* active low */
> > > +	value |= BYT_OUTPUT_EN;		/* disable output */
> > >  	writel(value, reg);
> > >  
> > >  	spin_unlock_irqrestore(&vg->lock, flags);
> > > @@ -319,6 +320,7 @@ static int byt_gpio_direction_output(struct gpio_chip *chip,
> > >  
> > >  	reg_val = readl(reg) | BYT_DIR_MASK;
> > >  	reg_val &= ~BYT_OUTPUT_EN;
> > > +	value |= BYT_INPUT_EN;		/* disable input */
> > >  
> > >  	if (value)
> > >  		writel(reg_val | BYT_LEVEL, reg);
> > > 
> > > completely untested however. Care to further explain why clearing both
> > > bits - thus enabling both INPUT and OUTPUT - is correct ?
> > 
> > Actually I really meant what I sent, but perhaps I misspoke during
> > explanation. We need to clear the bit to enable the functionality.
> > 
> > !BYT_INPUT_EN allows us to read the value. !BYT_OUTPUT_EN allows us to
> > set a value. If we want to set a value (acting as output) and still be
> > able to read via sysfs, we need to set both functionality (i.e. clear
> > both bits).
> > 
> > I'll resend the patch with a better comment.
> 
> Alright, just make sure that exposing a pin through sysfs and making it
> output high, then later switching it to input works. It looks like
> byt_gpio_direction_input() still needs to make sure OUTPUT is set.

I also noticed that this is missing:


(also untested)

ps: is BayTrail documentation available publicly ?

Comments

David Cohen Oct. 13, 2014, 8:19 p.m. UTC | #1
On Mon, Oct 13, 2014 at 02:36:18PM -0500, Felipe Balbi wrote:
> On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote:
> > Hi,
> > 
> > On Mon, Oct 13, 2014 at 12:24:04PM -0700, David Cohen wrote:
> > > On Mon, Oct 13, 2014 at 02:14:05PM -0500, Felipe Balbi wrote:
> > > > On Mon, Oct 13, 2014 at 11:23:59AM -0700, David Cohen wrote:
> > > > > Even if a gpio pin is set to output, we still need to set INPUT_EN bit
> > > > 
> > > > here you say you're setting that bit.
> > > > 
> > > > > to be able to read its value. Without this change, we'll always read low
> > > > > level state.
> > > > > 
> > > > > Cc: <stable@vger.kernel.org> # v3.14+
> > > > > Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
> > > > > ---
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > I'm resending same v1 patch but now copying linux stable and linux gpio.
> > > > > This patch is meant for all linux stable trees >= v3.14.
> > > > > 
> > > > > Br, David
> > > > > ---
> > > > > 
> > > > >  drivers/pinctrl/pinctrl-baytrail.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> > > > > index e12e5b07f6d7..c23d8ded936d 100644
> > > > > --- a/drivers/pinctrl/pinctrl-baytrail.c
> > > > > +++ b/drivers/pinctrl/pinctrl-baytrail.c
> > > > > @@ -318,7 +318,7 @@ static int byt_gpio_direction_output(struct gpio_chip *chip,
> > > > >  		"Potential Error: Setting GPIO with direct_irq_en to output");
> > > > >  
> > > > >  	reg_val = readl(reg) | BYT_DIR_MASK;
> > > > > -	reg_val &= ~BYT_OUTPUT_EN;
> > > > > +	reg_val &= ~(BYT_OUTPUT_EN | BYT_INPUT_EN);
> > > > 
> > > > but code is clearing it. Also, you're not patching byt_gpio_get(), so
> > > > you can't be 'reading its value' either. Quite frankly, this looks very
> > > > fishy to me. Comments on BYT_OUTPUT_EN and BYT_INPUT_EN states that
> > > > those bits are active low, meaning that clearing them enables that
> > > > particular feature.
> > > > 
> > > > How can you enable a pin to be both OUTPUT and INPUT ? Look like what
> > > > you really want is:
> > > > 
> > > > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> > > > index e12e5b0..69f882d 100644
> > > > --- a/drivers/pinctrl/pinctrl-baytrail.c
> > > > +++ b/drivers/pinctrl/pinctrl-baytrail.c
> > > > @@ -290,6 +290,7 @@ static int byt_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> > > >  
> > > >  	value = readl(reg) | BYT_DIR_MASK;
> > > >  	value &= ~BYT_INPUT_EN;		/* active low */
> > > > +	value |= BYT_OUTPUT_EN;		/* disable output */
> > > >  	writel(value, reg);
> > > >  
> > > >  	spin_unlock_irqrestore(&vg->lock, flags);
> > > > @@ -319,6 +320,7 @@ static int byt_gpio_direction_output(struct gpio_chip *chip,
> > > >  
> > > >  	reg_val = readl(reg) | BYT_DIR_MASK;
> > > >  	reg_val &= ~BYT_OUTPUT_EN;
> > > > +	value |= BYT_INPUT_EN;		/* disable input */
> > > >  
> > > >  	if (value)
> > > >  		writel(reg_val | BYT_LEVEL, reg);
> > > > 
> > > > completely untested however. Care to further explain why clearing both
> > > > bits - thus enabling both INPUT and OUTPUT - is correct ?
> > > 
> > > Actually I really meant what I sent, but perhaps I misspoke during
> > > explanation. We need to clear the bit to enable the functionality.
> > > 
> > > !BYT_INPUT_EN allows us to read the value. !BYT_OUTPUT_EN allows us to
> > > set a value. If we want to set a value (acting as output) and still be
> > > able to read via sysfs, we need to set both functionality (i.e. clear
> > > both bits).
> > > 
> > > I'll resend the patch with a better comment.
> > 
> > Alright, just make sure that exposing a pin through sysfs and making it
> > output high, then later switching it to input works. It looks like
> > byt_gpio_direction_input() still needs to make sure OUTPUT is set.
> 
> I also noticed that this is missing:
> 
> diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> index e12e5b0..7db5ab9 100644
> --- a/drivers/pinctrl/pinctrl-baytrail.c
> +++ b/drivers/pinctrl/pinctrl-baytrail.c
> @@ -614,3 +614,9 @@ static int __init byt_gpio_init(void)
>  }
>  
>  subsys_initcall(byt_gpio_init);
> +
> +static void __exit byt_gpio_exit(void)
> +{
> +	platform_driver_unregister(&byt_gpio_driver);
> +}
> +module_exit(byt_gpio_exit);
> 
> (also untested)

It sure does. Want to send a formal patch and I Ack?

> 
> ps: is BayTrail documentation available publicly ?

Check Minnowboard Max :) It's baytrail.

BR, David

> 
> -- 
> balbi


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Linus Walleij Oct. 28, 2014, 10:15 a.m. UTC | #2
On Mon, Oct 13, 2014 at 9:36 PM, Felipe Balbi <balbi@ti.com> wrote:
> On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote:

> I also noticed that this is missing:
>
> diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> index e12e5b0..7db5ab9 100644
> --- a/drivers/pinctrl/pinctrl-baytrail.c
> +++ b/drivers/pinctrl/pinctrl-baytrail.c
> @@ -614,3 +614,9 @@ static int __init byt_gpio_init(void)
>  }
>
>  subsys_initcall(byt_gpio_init);
> +
> +static void __exit byt_gpio_exit(void)
> +{
> +       platform_driver_unregister(&byt_gpio_driver);
> +}
> +module_exit(byt_gpio_exit);

But the Baytrail driver is not a loadable module, it is bool:

config PINCTRL_BAYTRAIL
        bool "Intel Baytrail GPIO pin control"
        depends on GPIOLIB && ACPI && X86

(...)

So I guess it won't need handling for removal, as it can only
be compiled-in.

Yours,
Linus Walleij
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Felipe Balbi Oct. 28, 2014, 2:42 p.m. UTC | #3
On Tue, Oct 28, 2014 at 11:15:20AM +0100, Linus Walleij wrote:
> On Mon, Oct 13, 2014 at 9:36 PM, Felipe Balbi <balbi@ti.com> wrote:
> > On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote:
> 
> > I also noticed that this is missing:
> >
> > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
> > index e12e5b0..7db5ab9 100644
> > --- a/drivers/pinctrl/pinctrl-baytrail.c
> > +++ b/drivers/pinctrl/pinctrl-baytrail.c
> > @@ -614,3 +614,9 @@ static int __init byt_gpio_init(void)
> >  }
> >
> >  subsys_initcall(byt_gpio_init);
> > +
> > +static void __exit byt_gpio_exit(void)
> > +{
> > +       platform_driver_unregister(&byt_gpio_driver);
> > +}
> > +module_exit(byt_gpio_exit);
> 
> But the Baytrail driver is not a loadable module, it is bool:
> 
> config PINCTRL_BAYTRAIL
>         bool "Intel Baytrail GPIO pin control"
>         depends on GPIOLIB && ACPI && X86
> 
> (...)
> 
> So I guess it won't need handling for removal, as it can only
> be compiled-in.

you can still unbind it through sysfs, right ? The thing also already
provides a ->remove() method anyway.
Linus Walleij Oct. 31, 2014, 8:12 a.m. UTC | #4
On Tue, Oct 28, 2014 at 3:42 PM, Felipe Balbi <balbi@ti.com> wrote:
> On Tue, Oct 28, 2014 at 11:15:20AM +0100, Linus Walleij wrote:
>> On Mon, Oct 13, 2014 at 9:36 PM, Felipe Balbi <balbi@ti.com> wrote:
>> > On Mon, Oct 13, 2014 at 02:26:32PM -0500, Felipe Balbi wrote:
>>
>> > I also noticed that this is missing:
>> >
>> > diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
>> > index e12e5b0..7db5ab9 100644
>> > --- a/drivers/pinctrl/pinctrl-baytrail.c
>> > +++ b/drivers/pinctrl/pinctrl-baytrail.c
>> > @@ -614,3 +614,9 @@ static int __init byt_gpio_init(void)
>> >  }
>> >
>> >  subsys_initcall(byt_gpio_init);
>> > +
>> > +static void __exit byt_gpio_exit(void)
>> > +{
>> > +       platform_driver_unregister(&byt_gpio_driver);
>> > +}
>> > +module_exit(byt_gpio_exit);
>>
>> But the Baytrail driver is not a loadable module, it is bool:
>>
>> config PINCTRL_BAYTRAIL
>>         bool "Intel Baytrail GPIO pin control"
>>         depends on GPIOLIB && ACPI && X86
>>
>> (...)
>>
>> So I guess it won't need handling for removal, as it can only
>> be compiled-in.
>
> you can still unbind it through sysfs, right ? The thing also already
> provides a ->remove() method anyway.

Yes you're right of course...

But another way to get rid of the dilemma is to set
.suppress_bind_attrs = true on the .driver field of the
device driver. The one can't unbind it through sysfs anymore.

        .driver = {
                .name   = "foo",
                .suppress_bind_attrs = true,
        },

So one of them need to be done.

I suspect this is a kind of common problem...

Yours,
Linus Walleij
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Patch
diff mbox

diff --git a/drivers/pinctrl/pinctrl-baytrail.c b/drivers/pinctrl/pinctrl-baytrail.c
index e12e5b0..7db5ab9 100644
--- a/drivers/pinctrl/pinctrl-baytrail.c
+++ b/drivers/pinctrl/pinctrl-baytrail.c
@@ -614,3 +614,9 @@  static int __init byt_gpio_init(void)
 }
 
 subsys_initcall(byt_gpio_init);
+
+static void __exit byt_gpio_exit(void)
+{
+	platform_driver_unregister(&byt_gpio_driver);
+}
+module_exit(byt_gpio_exit);