Commit 32d9b363 authored by Hans de Goede's avatar Hans de Goede Committed by Greg Kroah-Hartman
Browse files

i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes

commit c463a158


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.

This commit makes acpi_gsb_i2c_write_bytes() return 0 when i2c_transfer()
returns 1, so the single write transfer completed successfully, and
makes it return -EIO on for other (unexpected) return values >= 0.

Signed-off-by: default avatarHans de Goede <>
Acked-by: default avatarMika Westerberg <>
Signed-off-by: default avatarWolfram Sang <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 8c1bd0d0
......@@ -482,11 +482,16 @@ static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
msgs[0].buf = buffer;
ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
if (ret < 0)
dev_err(&client->adapter->dev, "i2c write failed\n");
return ret;
if (ret < 0) {
dev_err(&client->adapter->dev, "i2c write failed: %d\n", ret);
return ret;
/* 1 transfer must have completed successfully */
return (ret == 1) ? 0 : -EIO;
static acpi_status
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