misc: lis3lv02d: Fix false-positive WARN on various HP models
commit 3641762c1c9c7cfd84a7061a0a73054f09b412e3 upstream.
Before this commit lis3lv02d_get_pwron_wait() had a WARN_ONCE() to catch
a potential divide by 0. WARN macros should only be used to catch internal
kernel bugs and that is not the case here. We have been receiving a lot of
bug reports about kernel backtraces caused by this WARN.
The div value being checked comes from the lis3->odrs[] array. Which
is sized to be a power-of-2 matching the number of bits in lis3->odr_mask.
The only lis3 model where this array is not entirely filled with non zero
values. IOW the only model where we can hit the div == 0 check is the
3dc ("8 bits 3DC sensor") model:
int lis3_3dc_rates[16] = {0, 1, 10, 25, 50, 100, 200, 400, 1600, 5000};
Note the 0 value at index 0, according to the datasheet an odr index of 0
means "Power-down mode". HP typically uses a lis3 accelerometer for HDD
fall protection. What I believe is happening here is that on newer
HP devices, which only contain a SDD, the BIOS is leaving the lis3 device
powered-down since it is not used for HDD fall protection.
Note that the lis3_3dc_rates array initializer only specifies 10 values,
which matches the datasheet. So it also contains 6 zero values at the end.
Replace the WARN with a normal check, which treats an odr index of 0
as power-down and uses a normal dev_err() to report the error in case
odr index point past the initialized part of the array.
Fixes: 1510dd5954be ("lis3lv02d: avoid divide by zero due to unchecked")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=785814
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1817027
BugLink: https://bugs.centos.org/view.php?id=10720
Link: https://lore.kernel.org/r/20210217102501.31758-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed