[PATCH v2] pinctrl: intel: Actually disable Tx and Rx buffers on GPIO request

[PATCH v2] pinctrl: intel: Actually disable Tx and Rx buffers on GPIO request

[Andy Shevchenko]

Mistakenly the buffers (input and output) become enabled together for a short
period of time during GPIO request. This is problematic, because instead of
initial motive to disable them in the commit af7e3eeb84e2
("pinctrl: intel: Disable input and output buffer when switching to GPIO"),
the driven value on the pin, which might be used as an IRQ line, brings
firmwares of some touch pads to an awkward state that needs a full power off
to recover. Fix this, as stated in the culprit commit, by disabling the buffers.

Fixes: af7e3eeb84e2 ("pinctrl: intel: Disable input and output buffer when switching to GPIO")
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=210497
Reported-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v2: added tags, cosmetic fixes in the commit message
 drivers/pinctrl/intel/pinctrl-intel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c
index e77145e3b31b..5cd720f5b0e1 100644
--- a/drivers/pinctrl/intel/pinctrl-intel.c
+++ b/drivers/pinctrl/intel/pinctrl-intel.c
@@ -452,8 +452,8 @@ static void intel_gpio_set_gpio_mode(void __iomem *padcfg0)
 	value |= PADCFG0_PMODE_GPIO;
 
 	/* Disable input and output buffers */
-	value &= ~PADCFG0_GPIORXDIS;
-	value &= ~PADCFG0_GPIOTXDIS;
+	value |= PADCFG0_GPIORXDIS;
+	value |= PADCFG0_GPIOTXDIS;
 
 	/* Disable SCI/SMI/NMI generation */
 	value &= ~(PADCFG0_GPIROUTIOXAPIC | PADCFG0_GPIROUTSCI);
-- 
2.29.2

Re: [PATCH v2] pinctrl: intel: Actually disable Tx and Rx buffers on GPIO request

[Linus Walleij]

On Tue, Dec 8, 2020 at 7:24 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:

> Fixes: af7e3eeb84e2 ("pinctrl: intel: Disable input and output buffer when switching to GPIO")
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=210497

b4 strips this BugLink still! (I added it back manually.)

I'll try to report it.

Yours,
Linus Walleij