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@xxxxxxxxxxxxxxx
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
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
