On Sun, Apr 22, 2018 at 07:58:00PM +0200, Hans de Goede wrote:
> Unfortunately some DSDTs issue bogus i2c reads to non existing devices
> resulting in -EREMOTEIO errors because the non existing device of course
> does not ack.
>
> This happens e.g. from the The Asus T100TA's _BIX method, the DSDT on
> the T100TA defines 2 resources on the I2C1 bus:
>
> Name (EHID, ResourceTemplate ()
> {
> I2cSerialBusV2 (0x005B, ControllerInitiated, 0x00061A80,
> AddressingMode7Bit, "\\_SB.I2C1",
> 0x00, ResourceConsumer, , Exclusive,
> )
> })
> OperationRegion (EHOR, GenericSerialBus, Zero, 0x0100)
> Field (EHOR, BufferAcc, NoLock, Preserve)
> {
> Connection (EHID),
> Offset (0x01),
> AccessAs (BufferAcc, AttribBytes (0x10)),
> ABCD, 8
> }
>
> Name (UMPC, ResourceTemplate ()
> {
> I2cSerialBusV2 (0x0066, ControllerInitiated, 0x00061A80,
> AddressingMode7Bit, "\\_SB.I2C1",
> 0x00, ResourceConsumer, , Exclusive,
> )
> })
>
> The _BIX method does a single read (on each BIX() call) from the EHID
> device through the ABCD Field, only to completely ignore the result.
> This read always fails as there is no i2c client at address 0x5b.
>
> The _BIX method also does several reads from the UMPC device and actually
> uses the results of those to provide battery information.
>
> IIRC I've also seen some DSTDs which do an i2c read to detect if a device
> is present, also leading to false positive errors being logged.
>
> Esp. the _BIX use is problematic as the _BIX method gets called
> periodically to monitor battery status.
>
> This commit stops the logs from filling up with errors like these:
>
> [ 57.327858] i2c i2c-0: i2c read 16 bytes from client@0x5b starting at
> reg 0x1 failed, error: -121
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
