| Message ID | 20180812105321.2668-1-hdegoede@redhat.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2,1/2] i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes | expand |
On 2018-08-12 12:53, Hans de Goede wrote: > 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. I'm wondering if this might be fallout from one of 35cd67a0caf7 ("i2c: viperboard: return message count on master_xfer success") de9a8634f1cb ("i2c: pmcmsp: return message count on master_xfer success") But I have no idea what i2c driver these Thinkpads are using, so it is not unlikely that I'm way off... Cheers, Peter > Cc: stable@vger.kernel.org > Signed-off-by: Hans de Goede <hdegoede@redhat.com> > --- > Changes in v2: > -Modify the value which acpi_gsb_i2c_write_bytes() returns instead of > checking + modifying the return value in its caller
Hi, On 12-08-18 22:39, Peter Rosin wrote: > On 2018-08-12 12:53, Hans de Goede wrote: >> 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. > > I'm wondering if this might be fallout from one of > 35cd67a0caf7 ("i2c: viperboard: return message count on master_xfer success") > de9a8634f1cb ("i2c: pmcmsp: return message count on master_xfer success") No, these are using the designware driver, so these commits are not the cause, this simply is a long standing bug. Regards, Hans
On Sun, Aug 12, 2018 at 12:53:20PM +0200, Hans de Goede wrote: > 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. > > Cc: stable@vger.kernel.org > Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
On Sun, Aug 12, 2018 at 12:53:20PM +0200, Hans de Goede wrote: > 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. > > Cc: stable@vger.kernel.org > Signed-off-by: Hans de Goede <hdegoede@redhat.com> Applied to for-next, thanks!
diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c index 7c3b4740b94b..b8f303dea305 100644 --- a/drivers/i2c/i2c-core-acpi.c +++ b/drivers/i2c/i2c-core-acpi.c @@ -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"); kfree(buffer); - 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
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. Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- Changes in v2: -Modify the value which acpi_gsb_i2c_write_bytes() returns instead of checking + modifying the return value in its caller --- drivers/i2c/i2c-core-acpi.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)