From: Hans de Goede <hdegoede@redhat.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
Wolfram Sang <wsa@the-dreams.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
linux-acpi@vger.kernel.org, linux-i2c@vger.kernel.org,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] ACPI / PMIC: xpower: Block P-Unit I2C access during read-modify-write
Date: Sun, 23 Sep 2018 16:45:09 +0200 [thread overview]
Message-ID: <20180923144510.4564-3-hdegoede@redhat.com> (raw)
In-Reply-To: <20180923144510.4564-1-hdegoede@redhat.com>
intel_xpower_pmic_update_power() does a read-modify-write of the output
control register. The i2c-designware code blocks the P-Unit I2C access
during the read and write by taking the P-Unit's PMIC bus semaphore.
But between the read and the write that semaphore is released and the
P-Unit could make changes to the register which we then end up overwriting.
This commit makes intel_xpower_pmic_update_power() take the semaphore
itself so that it is held over the entire read-modify-write, avoiding this
race.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/acpi/pmic/intel_pmic_xpower.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/acpi/pmic/intel_pmic_xpower.c b/drivers/acpi/pmic/intel_pmic_xpower.c
index 316e55174aa9..9e6ddf2a2d4e 100644
--- a/drivers/acpi/pmic/intel_pmic_xpower.c
+++ b/drivers/acpi/pmic/intel_pmic_xpower.c
@@ -18,6 +18,7 @@
#include <linux/mfd/axp20x.h>
#include <linux/regmap.h>
#include <linux/platform_device.h>
+#include <asm/iosf_mbi.h>
#include "intel_pmic.h"
#define XPOWER_GPADC_LOW 0x5b
@@ -180,15 +181,21 @@ static int intel_xpower_pmic_get_power(struct regmap *regmap, int reg,
static int intel_xpower_pmic_update_power(struct regmap *regmap, int reg,
int bit, bool on)
{
- int data;
+ int data, ret;
/* GPIO1 LDO regulator needs special handling */
if (reg == XPOWER_GPI1_CTRL)
return regmap_update_bits(regmap, reg, GPI1_LDO_MASK,
on ? GPI1_LDO_ON : GPI1_LDO_OFF);
- if (regmap_read(regmap, reg, &data))
- return -EIO;
+ ret = iosf_mbi_block_punit_i2c_access();
+ if (ret)
+ return ret;
+
+ if (regmap_read(regmap, reg, &data)) {
+ ret = -EIO;
+ goto out;
+ }
if (on)
data |= BIT(bit);
@@ -196,9 +203,11 @@ static int intel_xpower_pmic_update_power(struct regmap *regmap, int reg,
data &= ~BIT(bit);
if (regmap_write(regmap, reg, data))
- return -EIO;
+ ret = -EIO;
+out:
+ iosf_mbi_unblock_punit_i2c_access();
- return 0;
+ return ret;
}
/**
--
2.19.0.rc1
next prev parent reply other threads:[~2018-09-23 14:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-23 14:45 [PATCH 0/3] x86: baytrail/cherrytrail: Rework and move P-Unit PMIC semaphore handling Hans de Goede
2018-09-23 14:45 ` [PATCH 1/3] x86: baytrail/cherrytrail: Rework and move P-Unit PMIC bus semaphore code Hans de Goede
2018-09-24 9:48 ` Andy Shevchenko
2018-10-11 10:14 ` Hans de Goede
2018-10-18 7:29 ` Rafael J. Wysocki
2018-10-18 7:36 ` Andy Shevchenko
2018-10-18 8:01 ` Jarkko Nikula
2018-10-18 8:34 ` Hans de Goede
2018-10-18 8:38 ` Rafael J. Wysocki
2018-10-18 8:47 ` Hans de Goede
2018-09-23 14:45 ` Hans de Goede [this message]
2018-09-23 14:45 ` [PATCH 3/3] i2c: designware: Cleanup bus lock handling Hans de Goede
2018-10-18 7:37 ` Wolfram Sang
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