| Message ID | 20221213144524.368297-1-rf@opensource.cirrus.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] i2c: designware: Fix unbalanced suspended flag | expand |
Hi On 12/14/22 13:28, Hans de Goede wrote: > Hi Richard, > > On 12/13/22 15:45, Richard Fitzgerald wrote: >> Ensure that i2c_mark_adapter_suspended() is always balanced by a call to >> i2c_mark_adapter_resumed(). >> >> dw_i2c_plat_resume() must always be called, so that >> i2c_mark_adapter_resumed() is called. This is not compatible with >> DPM_FLAG_MAY_SKIP_RESUME. >> >> The pairing of pm_runtime_force_suspend() and pm_runtime_force_resume() >> can replace this. If nothing is using the driver, and it is not currently >> suspended, it will be put into runtime-suspend and will be left in >> runtime-suspend during the system resume. >> >> pm_runtime_force_suspend() is not compatible with DPM_FLAG_SMART_SUSPEND >> so this must also be removed. DPM_FLAG_SMART_SUSPEND will set the device >> back to pm_runtime_active() during resume_noirq if it cannot skip resume. >> This would lead to the inconsistent state where the driver runtime_suspend >> has been called (by force_suspend()) but it is marked active (by PM core). >> >> The unbalanced suspended flag was introduced by >> commit c57813b8b288 ("i2c: designware: Lock the adapter while setting the >> suspended flag") >> >> Before that commit, the system and runtime PM used the same functions. The >> DPM_FLAG_MAY_SKIP_RESUME was used to skip the system resume if the driver >> had been in runtime-suspend. If system resume was skipped, the suspended >> flag would be cleared by the next runtime resume. The check of the >> suspended flag was _after_ the call to pm_runtime_get_sync() in >> i2c_dw_xfer(). So either a system resume or a runtime resume would clear >> the flag before it was checked. >> >> Having introduced the unbalanced suspended flag with that commit, a further >> commit 80704a84a9f8 ("i2c: designware: Use the >> i2c_mark_adapter_suspended/resumed() helpers") >> >> changed from using a local suspended flag to using the >> i2c_mark_adapter_suspended/resumed() functions. These use a flag that is >> checked by I2C core code before issuing the transfer to the bus driver, so >> there was no opportunity for the bus driver to runtime resume itself before >> the flag check. >> >> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> >> Fixes: c57813b8b288 ("i2c: designware: Lock the adapter while setting the suspended flag") > > Thank you. I like the new approach in this version. > > Reviewed-by: Hans de Goede <hdegoede@redhat.com> > I noticed a resume regression with this patch but not all machines and only when resuming from s2idle. After resume all devices on those machines are in D0 even their runtime state show they are suspended. Works with v6.1. - Baytrail based MRD7 with one I2C bus shared with PUNIT After boot. All ok (5th bus is shared with PUNIT and not power managed) cat /sys/bus/platform/devices/80860F41\:0*/power/runtime_status suspended suspended suspended suspended active cat /sys/bus/platform/devices/80860F41\:0*/firmware_node/power_state D3hot D3hot D3hot D3hot D0 After suspend-to-idle (s2idle) resume cycle. Devices stay in D0 cat /sys/bus/platform/devices/80860F41\:0*/power/runtime_status suspended suspended suspended suspended active cat /sys/bus/platform/devices/80860F41\:0*/firmware_node/power_state D0 D0 D0 D0 D0 - Braswell based reference board After boot or after suspend-to-ram resume. All ok cat /sys/bus/platform/devices/808622C1\:0*/power/runtime_status suspended suspended suspended suspended suspended suspended cat /sys/bus/platform/devices/808622C1\:0*/firmware_node/power_state D3hot D3hot D3hot D3hot D3hot D3hot After suspend-to-idle resume. Devices stay in D0 cat /sys/bus/platform/devices/808622C1\:0*/power/runtime_status suspended suspended suspended suspended suspended suspended cat /sys/bus/platform/devices/808622C1\:0*/firmware_node/power_state D0 D0 D0 D0 D0 D0 - Newer machines (Skylake and newer) where i2c-designware is part of Intel Low Power Subsystem (LPSS) Patch doesn't seem to cause regression and after s2idle resume I2C devices are in D3hot. Jarkko
Hi, On 12/15/22 16:09, Jarkko Nikula wrote: > Hi > > On 12/14/22 13:28, Hans de Goede wrote: >> Hi Richard, >> >> On 12/13/22 15:45, Richard Fitzgerald wrote: >>> Ensure that i2c_mark_adapter_suspended() is always balanced by a call to >>> i2c_mark_adapter_resumed(). >>> >>> dw_i2c_plat_resume() must always be called, so that >>> i2c_mark_adapter_resumed() is called. This is not compatible with >>> DPM_FLAG_MAY_SKIP_RESUME. >>> >>> The pairing of pm_runtime_force_suspend() and pm_runtime_force_resume() >>> can replace this. If nothing is using the driver, and it is not currently >>> suspended, it will be put into runtime-suspend and will be left in >>> runtime-suspend during the system resume. >>> >>> pm_runtime_force_suspend() is not compatible with DPM_FLAG_SMART_SUSPEND >>> so this must also be removed. DPM_FLAG_SMART_SUSPEND will set the device >>> back to pm_runtime_active() during resume_noirq if it cannot skip resume. >>> This would lead to the inconsistent state where the driver runtime_suspend >>> has been called (by force_suspend()) but it is marked active (by PM core). >>> >>> The unbalanced suspended flag was introduced by >>> commit c57813b8b288 ("i2c: designware: Lock the adapter while setting the >>> suspended flag") >>> >>> Before that commit, the system and runtime PM used the same functions. The >>> DPM_FLAG_MAY_SKIP_RESUME was used to skip the system resume if the driver >>> had been in runtime-suspend. If system resume was skipped, the suspended >>> flag would be cleared by the next runtime resume. The check of the >>> suspended flag was _after_ the call to pm_runtime_get_sync() in >>> i2c_dw_xfer(). So either a system resume or a runtime resume would clear >>> the flag before it was checked. >>> >>> Having introduced the unbalanced suspended flag with that commit, a further >>> commit 80704a84a9f8 ("i2c: designware: Use the >>> i2c_mark_adapter_suspended/resumed() helpers") >>> >>> changed from using a local suspended flag to using the >>> i2c_mark_adapter_suspended/resumed() functions. These use a flag that is >>> checked by I2C core code before issuing the transfer to the bus driver, so >>> there was no opportunity for the bus driver to runtime resume itself before >>> the flag check. >>> >>> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> >>> Fixes: c57813b8b288 ("i2c: designware: Lock the adapter while setting the suspended flag") >> >> Thank you. I like the new approach in this version. >> >> Reviewed-by: Hans de Goede <hdegoede@redhat.com> >> > I noticed a resume regression with this patch but not all machines and only when resuming from s2idle. After resume all devices on those machines are in D0 even their runtime state show they are suspended. Works with v6.1. > > - Baytrail based MRD7 with one I2C bus shared with PUNIT > > After boot. All ok (5th bus is shared with PUNIT and not power managed) > > cat /sys/bus/platform/devices/80860F41\:0*/power/runtime_status > suspended > suspended > suspended > suspended > active > > cat /sys/bus/platform/devices/80860F41\:0*/firmware_node/power_state > D3hot > D3hot > D3hot > D3hot > D0 > > After suspend-to-idle (s2idle) resume cycle. Devices stay in D0 > > cat /sys/bus/platform/devices/80860F41\:0*/power/runtime_status > suspended > suspended > suspended > suspended > active > > cat /sys/bus/platform/devices/80860F41\:0*/firmware_node/power_state > D0 > D0 > D0 > D0 > D0 Ah yes this makes sense. We leave the device runtime-suspended, but since the system-level resume handler does run, the ACPI pm domain resume handler also has ran before calling the driver level callback and the acpi pm domain handler will have put the device in D0 before calling the driver level resume handler. So now the device actually is in D0 while the pm-core thinks it is left in runtime-suspended state, so it will not runtime suspend it later, as would happen when not using force_runtime-suspend + force-runtime-resume (*). So yeah this is not going to work. I think instead we need to go back to v1 together with the changes which I proposed for v1. As I mentioned when reviewing v1, v1 is not prefect, but it really is an ok solution to this. Regards, Hans *) which does not actually always runtime resume despite its name
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c index ba043b547393..590503e56bd0 100644 --- a/drivers/i2c/busses/i2c-designware-platdrv.c +++ b/drivers/i2c/busses/i2c-designware-platdrv.c @@ -349,17 +349,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) adap->dev.of_node = pdev->dev.of_node; adap->nr = -1; - if (dev->flags & ACCESS_NO_IRQ_SUSPEND) { - dev_pm_set_driver_flags(&pdev->dev, - DPM_FLAG_SMART_PREPARE | - DPM_FLAG_MAY_SKIP_RESUME); - } else { - dev_pm_set_driver_flags(&pdev->dev, - DPM_FLAG_SMART_PREPARE | - DPM_FLAG_SMART_SUSPEND | - DPM_FLAG_MAY_SKIP_RESUME); - } - + dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_SMART_PREPARE); device_enable_async_suspend(&pdev->dev); /* The code below assumes runtime PM to be disabled. */ @@ -453,10 +443,15 @@ static int dw_i2c_plat_runtime_suspend(struct device *dev) static int __maybe_unused dw_i2c_plat_suspend(struct device *dev) { struct dw_i2c_dev *i_dev = dev_get_drvdata(dev); + int ret; + + ret = pm_runtime_force_suspend(dev); + if (ret) + return ret; i2c_mark_adapter_suspended(&i_dev->adapter); - return dw_i2c_plat_runtime_suspend(dev); + return 0; } static int dw_i2c_plat_runtime_resume(struct device *dev) @@ -474,8 +469,13 @@ static int dw_i2c_plat_runtime_resume(struct device *dev) static int __maybe_unused dw_i2c_plat_resume(struct device *dev) { struct dw_i2c_dev *i_dev = dev_get_drvdata(dev); + int ret; + + /* Resume if pm_runtime_force_suspend() suspended. */ + ret = pm_runtime_force_resume(dev); + if (ret) + return ret; - dw_i2c_plat_runtime_resume(dev); i2c_mark_adapter_resumed(&i_dev->adapter); return 0;
Ensure that i2c_mark_adapter_suspended() is always balanced by a call to i2c_mark_adapter_resumed(). dw_i2c_plat_resume() must always be called, so that i2c_mark_adapter_resumed() is called. This is not compatible with DPM_FLAG_MAY_SKIP_RESUME. The pairing of pm_runtime_force_suspend() and pm_runtime_force_resume() can replace this. If nothing is using the driver, and it is not currently suspended, it will be put into runtime-suspend and will be left in runtime-suspend during the system resume. pm_runtime_force_suspend() is not compatible with DPM_FLAG_SMART_SUSPEND so this must also be removed. DPM_FLAG_SMART_SUSPEND will set the device back to pm_runtime_active() during resume_noirq if it cannot skip resume. This would lead to the inconsistent state where the driver runtime_suspend has been called (by force_suspend()) but it is marked active (by PM core). The unbalanced suspended flag was introduced by commit c57813b8b288 ("i2c: designware: Lock the adapter while setting the suspended flag") Before that commit, the system and runtime PM used the same functions. The DPM_FLAG_MAY_SKIP_RESUME was used to skip the system resume if the driver had been in runtime-suspend. If system resume was skipped, the suspended flag would be cleared by the next runtime resume. The check of the suspended flag was _after_ the call to pm_runtime_get_sync() in i2c_dw_xfer(). So either a system resume or a runtime resume would clear the flag before it was checked. Having introduced the unbalanced suspended flag with that commit, a further commit 80704a84a9f8 ("i2c: designware: Use the i2c_mark_adapter_suspended/resumed() helpers") changed from using a local suspended flag to using the i2c_mark_adapter_suspended/resumed() functions. These use a flag that is checked by I2C core code before issuing the transfer to the bus driver, so there was no opportunity for the bus driver to runtime resume itself before the flag check. Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Fixes: c57813b8b288 ("i2c: designware: Lock the adapter while setting the suspended flag") --- drivers/i2c/busses/i2c-designware-platdrv.c | 26 ++++++++++----------- 1 file changed, 13 insertions(+), 13 deletions(-)