Hi! > > > From: Rafael J. Wysocki <rjw@xxxxxxx> > > > > > > Some time ago it turned out that our suspend code ordering broke > > > some NVidia-based systems that hung if _PTS was executed with one of > > > the PCI devices, specifically a USB controller, in a low power state. > > > Then, it was noticed that the suspend code ordering was not compliant > > > with ACPI 1.0, although it was compliant with ACPI 2.0 (and later), > > > and it was argued that the code had to be changed for that reason > > > (ref. http://bugzilla.kernel.org/show_bug.cgi?id=9528). So we did, > > > but evidently we did wrong, because it's now turning out that some > > > systems have been broken by this change (refs. > > > http://bugzilla.kernel.org/show_bug.cgi?id=10340 , > > > https://bugzilla.novell.com/show_bug.cgi?id=374217#c16). [I said > > > at that time that something like this might happend, but the majority > > > of people involved thought that it was improbable due to the > > > necessity to preserve the compliance of hardware with ACPI 1.0.] > > > This actually is a quite serious regression from 2.6.24. > > > > > > Moreover, the ACPI 1.0 ordering of suspend code introduced another > > > issue that I have only noticed recently. Namely, if the suspend of > > > one of devices fails, the already suspended devices will be resumed > > > without executing _WAK before, which leads to problems on some > > > systems (for example, in such situations thermal management is > > > broken on my HP nx6325). Consequently, it also breaks suspend > > > debugging on the affected systems. > > > > > > Note also, that the requirement to execute _PTS before suspending > > > devices does not really make sense, because the device in question > > > may be put into a low power state at run time for a reason unrelated > > > to a system-wide suspend. Yes, but if we are putting them into lowpower state ourselves, we should probably be doing that "by hand", without calling acpi methods. _PTS may prepare something for acpi methods (which tell us which PCI Dx state to put the device in at the very least). > > > For the reasons outlined above, the change of the suspend ordering > > > should be reverted, which is done by the patch below. > > > > But this will break those few nvidia-based systems, no? > > > > this may have been a good idea in -rc1 days, but we are in -rc7 > > now... and the patch is slightly big. > > It's quite obvious, though. Yes, but breaking systems between -rc7 and final is _very_ unnice. > > What about something like: (hand-edited patch, sorry) > > Well, I think that would be confusing. > > The NVidia systems are broken anyway on 2.6.24.x, so we just don't fix them > rather than break them and there are more reasons to do what the patch does > (as pointed out in the changelog). For example, your suggested patch doesn't > fix the error paths/debugging breakage described in the changelog. But that should not be impossible to fix, right? > I think we _can_ do something about the failing NVidia systems in the 2.6.26 > time frame, but that will require some more consideration. We could simply blacklist them, no? Pavel > > Index: linux-2.6/drivers/acpi/sleep/main.c > > =================================================================== > > --- linux-2.6.orig/drivers/acpi/sleep/main.c > > +++ linux-2.6/drivers/acpi/sleep/main.c > > @@ -26,21 +26,6 @@ u8 sleep_states[ACPI_S_STATE_COUNT]; > > > > #ifdef CONFIG_PM_SLEEP > > static u32 acpi_target_sleep_state = ACPI_STATE_S0; > > static bool acpi_sleep_finish_wake_up; > > > > - /* > > - * ACPI 2.0 and later want us to execute _PTS after suspending devices, so we > > - * allow the user to request that behavior by using the 'acpi_new_pts_ordering' > > - * kernel command line option that causes the following variable to be set. > > - */ > > static bool new_pts_ordering = true; > > > > -static int __init acpi_new_pts_ordering(char *str) > > +static int __init acpi_old_pts_ordering(char *str) > > { > > new_pts_ordering = false; > > return 1; > > } > > -__setup("acpi_old_pts_ordering", acpi_old_pts_ordering); > > +__setup("acpi_new_pts_ordering", acpi_new_pts_ordering); > > #endif > > > > static int acpi_sleep_prepare(u32 acpi_state) > > Index: linux-2.6/Documentation/kernel-parameters.txt > > =================================================================== > > --- linux-2.6.orig/Documentation/kernel-parameters.txt > > +++ linux-2.6/Documentation/kernel-parameters.txt > > @@ -170,11 +170,6 @@ and is between 256 and 4096 characters. > > acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA > > Format: <irq>,<irq>... > > > > - acpi_new_pts_ordering [HW,ACPI] > > + acpi_old_pts_ordering [HW,ACPI] > > - Enforce the ACPI 2.0 ordering of the _PTS control > > + Enforce the ACPI 1.0 ordering of the _PTS control > > method wrt putting devices into low power states > > - default: pre ACPI 2.0 ordering of _PTS > > + default: ACPI 2.0 ordering of _PTS > > > > acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT > > > > acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS > > > > Thanks, > Rafael > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
