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 hdegoede@redhat.com --- 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;