Re: FAILED: patch "[PATCH] iio: imu: st_lsm6dsx: Fix selection of ST_LSM6DS3_ID" failed to apply to 4.19-stable tree

[Sasha Levin <sashal@kernel.org>]

On Sun, Jan 19, 2020 at 08:10:32PM +0100, Stephan Gerhold wrote:
>On Sun, Jan 19, 2020 at 01:55:30PM -0500, Sasha Levin wrote:
>> On Sun, Jan 19, 2020 at 05:15:33PM +0100, Stephan Gerhold wrote:
>> > On Sun, Jan 19, 2020 at 10:32:53AM -0500, Sasha Levin wrote:
>> > > On Sun, Jan 19, 2020 at 02:33:30PM +0100, gregkh@linuxfoundation.org wrote:
>> > > >
>> > > > The patch below does not apply to the 4.19-stable tree.
>> > > > If someone wants it applied there, or to any other stable or longterm
>> > > > tree, then please email the backport, including the original git commit
>> > > > id to <stable@vger.kernel.org>.
>> > > >
>> > > > thanks,
>> > > >
>> > > > greg k-h
>> > > >
>> > > > ------------------ original commit in Linus's tree ------------------
>> > > >
>> > > > From fb4fbc8904e786537e29329d791147389e1465a2 Mon Sep 17 00:00:00 2001
>> > > > From: Stephan Gerhold <stephan@gerhold.net>
>> > > > Date: Mon, 16 Dec 2019 13:41:20 +0100
>> > > > Subject: [PATCH] iio: imu: st_lsm6dsx: Fix selection of ST_LSM6DS3_ID
>> > > >
>> > > > At the moment, attempting to probe a device with ST_LSM6DS3_ID
>> > > > (e.g. using the st,lsm6ds3 compatible) fails with:
>> > > >
>> > > >    st_lsm6dsx_i2c 1-006b: unsupported whoami [69]
>> > > >
>> > > > ... even though 0x69 is the whoami listed for ST_LSM6DS3_ID.
>> > > >
>> > > > This happens because st_lsm6dsx_check_whoami() also attempts
>> > > > to match unspecified (zero-initialized) entries in the "id" array.
>> > > > ST_LSM6DS3_ID = 0 will therefore match any entry in
>> > > > st_lsm6dsx_sensor_settings (here: the first), because none of them
>> > > > actually have all 12 entries listed in the "id" array.
>> > > >
>> > > > Avoid this by additionally checking if "name" is set,
>> > > > which is only set for valid entries in the "id" array.
>> > > >
>> > > > Note: Although the problem was introduced earlier it did not surface until
>> > > > commit 52f4b1f19679 ("iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9ds1")
>> > > > because ST_LSM6DS3_ID was the first entry in st_lsm6dsx_sensor_settings.
>> > > >
>> > > > Fixes: d068e4a0f921 ("iio: imu: st_lsm6dsx: add support to multiple devices with the same settings")
>> > > > Cc: <stable@vger.kernel.org> # 5.4
>> > > > Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
>> > > > Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
>> > > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> > >
>> > > I don't think that this is needed on anything older than 5.4 because
>> > > they don't have 801a6e0af0c6 ("iio: imu: st_lsm6dsx: add support to
>> > > LSM6DSO"), the fixes tag might be misleading here a bit.
>> >
>> > Correct. I didn't want to use 801a6e0af0c6 ("iio: imu: st_lsm6dsx: add
>> > support to LSM6DSO") as Fixes tag because that commit did not do
>> > anything wrong - the problem was introduced earlier, but there is no way
>> > to trigger it on older kernels.
>> >
>> > This is why I added # 5.5 to the Cc: stable tag.
>> > Are these comments still used in any way?
>> > Or is there a better way to encode this into the commit message?
>>
>> Usually if there's a fixes: tag we'll look at that rather than the
>> version appended to the stable tag.
>>
>> Consider maybe using two "Fixes:" tags to point at the commits that were
>> involved.
>
>So basically this
>
>Fixes: d068e4a0f921 ("iio: imu: st_lsm6dsx: add support to multiple devices with the same settings")
>Fixes: 52f4b1f19679 ("iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9ds1")
>
>would mean "fixes the combination of these two commits"?

Yup!

-- 
Thanks,
Sasha