linux-kernel - [PATCH 5.4 004/453] pinctrl: merrifield: Set default bias in case no particular value given

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Message-Id: <20201228124937.452678150@linuxfoundation.org>
Date:   Mon, 28 Dec 2020 13:44:00 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 004/453] pinctrl: merrifield: Set default bias in case no particular value given

From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

[ Upstream commit 0fa86fc2e28227f1e64f13867e73cf864c6d25ad ]

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@...ux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 04ca8ae95df83..9e91d83b01388 100644
--- a/drivers/pinctrl/intel/pinctrl-merrifield.c
+++ b/drivers/pinctrl/intel/pinctrl-merrifield.c
@@ -741,6 +741,10 @@ 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;
@@ -761,6 +765,10 @@ 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;
-- 
2.27.0