On 4/7/20 10:30 PM, Rafael J. Wysocki wrote:
On Tue, Apr 7, 2020 at 8:11 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: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.OK Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Acked-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
