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| Filename | Latest commit message | Latest commit date |
|---|---|---|
653b425309
commit d79294d0de12ddd1420110813626d691f440b86f upstream.
We already set DPM_FLAG_SMART_PREPARE, so we completely skip all
callbacks (other then prepare) where possible, quoting from
dw_i2c_plat_prepare():
/*
* If the ACPI companion device object is present for this device, it
* may be accessed during suspend and resume of other devices via I2C
* operation regions, so tell the PM core and middle layers to avoid
* skipping system suspend/resume callbacks for it in that case.
*/
return !has_acpi_companion(dev);
Also setting the DPM_FLAG_SMART_SUSPEND will cause acpi_subsys_suspend()
to leave the controller runtime-suspended even if dw_i2c_plat_prepare()
returned 0.
Leaving the controller runtime-suspended normally, when the I2C controller
is suspended during the suspend_late phase, is not an issue because
the pm_runtime_get_sync() done by i2c_dw_xfer() will (runtime-)resume it.
But for dw I2C controllers on Bay- and Cherry-Trail devices acpi_lpss.c
leaves the controller alive until the suspend_noirq phase, because it may
be used by the _PS3 ACPI methods of PCI devices and PCI devices are left
powered on until the suspend_noirq phase.
Between the suspend_late and resume_early phases runtime-pm is disabled.
So for any ACPI I2C OPRegion accesses done after the suspend_late phase,
the pm_runtime_get_sync() done by i2c_dw_xfer() is a no-op and the
controller is left runtime-suspended.
i2c_dw_xfer() has a check to catch this condition (rather then waiting
for the I2C transfer to timeout because the controller is suspended).
acpi_subsys_suspend() leaving the controller runtime-suspended in
combination with an ACPI I2C OPRegion access done after the suspend_late
phase triggers this check, leading to the following error being logged
on a Bay Trail based Lenovo Thinkpad 8 tablet:
[ 93.275882] i2c_designware 80860F41:00: Transfer while suspended
[ 93.275993] WARNING: CPU: 0 PID: 412 at drivers/i2c/busses/i2c-designware-master.c:429 i2c_dw_xfer+0x239/0x280
...
[ 93.276252] Workqueue: kacpi_notify acpi_os_execute_deferred
[ 93.276267] RIP: 0010:i2c_dw_xfer+0x239/0x280
...
[ 93.276340] Call Trace:
[ 93.276366] __i2c_transfer+0x121/0x520
[ 93.276379] i2c_transfer+0x4c/0x100
[ 93.276392] i2c_acpi_space_handler+0x219/0x510
[ 93.276408] ? up+0x40/0x60
[ 93.276419] ? i2c_acpi_notify+0x130/0x130
[ 93.276433] acpi_ev_address_space_dispatch+0x1e1/0x252
...
So since on BYT and CHT platforms we want ACPI I2c OPRegion accesses
to work until the suspend_noirq phase, we need the controller to be
runtime-resumed during the suspend phase if it is runtime-suspended
suspended at that time. This means that we must not set the
DPM_FLAG_SMART_SUSPEND on these platforms.
On BYT and CHT we already have a special ACCESS_NO_IRQ_SUSPEND flag
to make sure the controller stays functional until the suspend_noirq
phase. This commit makes the driver not set the DPM_FLAG_SMART_SUSPEND
flag when that flag is set.
Cc: stable@vger.kernel.org
Fixes:
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Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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