[PATCH v1] pinctrl: merrifield: Set default bias in case no particular value given

[PATCH v1] pinctrl: merrifield: Set default bias in case no particular value given

[Andy Shevchenko]

When GPIO library asks pin control to set the bias, it doesn't pass
any value of it and argument is considered boolean (and this is true
for ACPI GpioIo() / GpioInt() resources, by the way). Thus, individual
drivers must behave well, when they got the resistance value of 1 Ohm,
i.e. transforming it to sane default.

In case of Intel Merrifield pin control hardware the 20 kOhm sounds plausible
because it gives a good trade off between weakness and minimization of leakage
current (will be only 50 uA with the above choice).

Fixes: 4e80c8f50574 ("pinctrl: intel: Add Intel Merrifield pin controller support")
Depends-on: 2956b5d94a76 ("pinctrl / gpio: Introduce .set_config() callback for GPIO chips")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/pinctrl/intel/pinctrl-merrifield.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pinctrl/intel/pinctrl-merrifield.c b/drivers/pinctrl/intel/pinctrl-merrifield.c
index e4ff8da1b894..3ae141e0b421 100644
--- a/drivers/pinctrl/intel/pinctrl-merrifield.c
+++ b/drivers/pinctrl/intel/pinctrl-merrifield.c
@@ -745,6 +745,10 @@ static int mrfld_config_set_pin(struct mrfld_pinctrl *mp, unsigned int pin,
 		mask |= BUFCFG_Px_EN_MASK | BUFCFG_PUPD_VAL_MASK;
 		bits |= BUFCFG_PU_EN;
 
+		/* Set default strength value in case none is given */
+		if (arg == 1)
+			arg = 20000;
+
 		switch (arg) {
 		case 50000:
 			bits |= BUFCFG_PUPD_VAL_50K << BUFCFG_PUPD_VAL_SHIFT;
@@ -765,6 +769,10 @@ static int mrfld_config_set_pin(struct mrfld_pinctrl *mp, unsigned int pin,
 		mask |= BUFCFG_Px_EN_MASK | BUFCFG_PUPD_VAL_MASK;
 		bits |= BUFCFG_PD_EN;
 
+		/* Set default strength value in case none is given */
+		if (arg == 1)
+			arg = 20000;
+
 		switch (arg) {
 		case 50000:
 			bits |= BUFCFG_PUPD_VAL_50K << BUFCFG_PUPD_VAL_SHIFT;
-- 
2.28.0

Re: [PATCH v1] pinctrl: merrifield: Set default bias in case no particular value given

[Mika Westerberg]

On Wed, Nov 11, 2020 at 02:06:05PM +0200, Andy Shevchenko wrote:
> When GPIO library asks pin control to set the bias, it doesn't pass
> any value of it and argument is considered boolean (and this is true
> for ACPI GpioIo() / GpioInt() resources, by the way). Thus, individual
> drivers must behave well, when they got the resistance value of 1 Ohm,
> i.e. transforming it to sane default.
> 
> In case of Intel Merrifield pin control hardware the 20 kOhm sounds plausible
> because it gives a good trade off between weakness and minimization of leakage
> current (will be only 50 uA with the above choice).
> 
> Fixes: 4e80c8f50574 ("pinctrl: intel: Add Intel Merrifield pin controller support")
> Depends-on: 2956b5d94a76 ("pinctrl / gpio: Introduce .set_config() callback for GPIO chips")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Re: [PATCH v1] pinctrl: merrifield: Set default bias in case no particular value given

[Andy Shevchenko]

On Thu, Nov 12, 2020 at 10:06:50AM +0200, Mika Westerberg wrote:
> On Wed, Nov 11, 2020 at 02:06:05PM +0200, Andy Shevchenko wrote:
> > When GPIO library asks pin control to set the bias, it doesn't pass
> > any value of it and argument is considered boolean (and this is true
> > for ACPI GpioIo() / GpioInt() resources, by the way). Thus, individual
> > drivers must behave well, when they got the resistance value of 1 Ohm,
> > i.e. transforming it to sane default.
> > 
> > In case of Intel Merrifield pin control hardware the 20 kOhm sounds plausible
> > because it gives a good trade off between weakness and minimization of leakage
> > current (will be only 50 uA with the above choice).
> > 
> > Fixes: 4e80c8f50574 ("pinctrl: intel: Add Intel Merrifield pin controller support")
> > Depends-on: 2956b5d94a76 ("pinctrl / gpio: Introduce .set_config() callback for GPIO chips")
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Pushed to my review and testing queue, thanks!

-- 
With Best Regards,
Andy Shevchenko