From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: [PATCH] i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes Date: Fri, 10 Aug 2018 14:27:14 +0200 Message-ID: <20180810122714.690-1-hdegoede@redhat.com> Return-path: Sender: stable-owner@vger.kernel.org To: Wolfram Sang , Mika Westerberg Cc: Hans de Goede , linux-i2c@vger.kernel.org, linux-acpi@vger.kernel.org, stable@vger.kernel.org List-Id: linux-acpi@vger.kernel.org acpi_gsb_i2c_write_bytes() returns i2c_transfer()'s return value, which is the number of transfers executed on success, so 1. The ACPI code expects us to store 0 in gsb->status for success, not 1. Specifically this breaks the following code in the Thinkpad 8 DSDT: ECWR = I2CW = ECWR /* \_SB_.I2C1.BAT0.ECWR */ If ((ECST == Zero)) { ECRD = I2CR /* \_SB_.I2C1.I2CR */ } Before this commit we set ECST to 1, causing the read to never happen breaking battery monitoring on the Thinkpad 8. Note the Thinkpad 8 also has some unrelated issues where i2c transfers are unreliable. This commit sets status to 0 if it was bigger then 0 (so success), mirroring the multi-byte read path, fixing this. Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede --- drivers/i2c/i2c-core-acpi.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c index 7c3b4740b94b..10ad851bd277 100644 --- a/drivers/i2c/i2c-core-acpi.c +++ b/drivers/i2c/i2c-core-acpi.c @@ -595,6 +595,8 @@ i2c_acpi_space_handler(u32 function, acpi_physical_address command, } else { status = acpi_gsb_i2c_write_bytes(client, command, gsb->data, info->access_length); + if (status > 0) + status = 0; } break; -- 2.18.0