ACPI / PMIC: xpower: Block P-Unit I2C access during read-modify-write (3c670dba) · Commits · 戴 / test

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> Signed-off-by:

Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/pmic/intel_pmic_xpower.c

+15 −6

Original line number	Diff line number	Diff line
		@@ -8,8 +8,9 @@
		#include <linux/acpi.h>
		#include <linux/init.h>
		#include <linux/mfd/axp20x.h>
		#include <linux/platform_device.h>
		#include <linux/regmap.h>
		#include <linux/platform_device.h>
		#include <asm/iosf_mbi.h>
		#include "intel_pmic.h"

		#define XPOWER_GPADC_LOW 0x5b
		@@ -172,15 +173,21 @@ 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);
		@@ -188,9 +195,11 @@ 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;
		}

		/**

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