From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede 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 Message-ID: <20180923144510.4564-3-hdegoede@redhat.com> References: <20180923144510.4564-1-hdegoede@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180923144510.4564-1-hdegoede@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Andy Shevchenko , Mika Westerberg , Jarkko Nikula , Wolfram Sang , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: Hans de Goede , linux-acpi@vger.kernel.org, linux-i2c@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org List-Id: linux-i2c@vger.kernel.org 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 --- 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 #include #include +#include #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