Hi Paul,
On 03/31/2017 12:17 AM, Paul Menzel wrote:
Dear Wolfram,
Thank you for the reply, which we talked about briefly at the
Chemnitzer LinuxTage.
Am Freitag, den 03.03.2017, 11:17 +0100 schrieb Wolfram Sang:
Unfortunately, commit 2fee61d22e (i2c: piix4: Add support for
multiplexed main adapter in SB800) [1] caused a regression. Tim
reported that to the Linux Kernel Bugtracker as bug #170741 last
September [2], but it looks like the affected subsystems don’t use it.
Jean Delvare pointed out this issue amongst others[1] last year already.
Let me quote:
===
5* The I/O ports used for SMBus configuration and port switching are
also needed by a watchdog driver, sp5100_tco. Both drivers request the
region, so the first one wins, and the other driver can't be loaded.
sp5100_tco was there first, so the changes done to the i2c-piix4 driver
recently will cause a regression for some users by preventing them
from using the sp5100_tco and i2c-piix4 drivers at the same time. In
the long run I guess we will need a helper module to handle this shared
resource. Unless IORESOURCE_MUXED can be used for that. Either way,
that's more work than I can put into this before kernel v4.5 is
released. For the time being, I think we should simply make it
non-fatal if the I/O ports can't be requested, and continue without
multiplexing (as before.)
===
Seems nobody had the resources, so far.
I still don’t understand, why Jean then not immediately reverted the
commit to adhere to the Linux Kernel’s no-regression-policy.
I don't have the HW and not much experience with non-embedded
platforms. I wonder, though, if we really need to convert the drivers
to MFD ones, or if we could use the simpler MFD_SYSCON mechanism
which helps in exactly such cases for embedded platforms. But I am
really lacking details here and am afraid this is probably all the
input I can give currently.
Zoltan stepped up, and uploaded a patch for review to the Kernel.org
Bugzilla [2], also attached to this message.
Please don't send patches as attachments.
request_muxed_region() can fail, and literally every other driver
using it checks for that failure. Please do the same.
The sp5100_tco_dev_name change in the watchdog driver is unnecessary.
There are some unnecessary { } in the watchdog driver after the patch
is applied.
Please split the patch into two patches so they can be reviewed and
applied separately.
Thanks,
Guenter
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