| Message ID | alpine.LFD.2.00.0904222223200.21119@localhost.localdomain (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
* Len Brown <lenb@kernel.org> wrote: > From: Len Brown <len.brown@intel.com> > > Linux tells ICH4 users that they can (manually) invoke > "hpet=force" to enable the undocumented HPET. > The HPET becomes available for both clocksource and clockevents. > > But as of ff69f2bba67bd45514923aaedbf40fe351787c59 > (acpi: fix of pmtimer overflow that make Cx states time incorrect) > the hpet may be used for idle accounting, and > hpet=force on an ICH4 box hangs boot. > > It turns out that reading the HPET timer immediately > after return from C3 hangs. > > Well, the reason we enable the HPET on these systems > is primarily for clockevents -- the HPET has a longer > maximum timer duration than the PIT. HPET as a clocksource > is less interesting. > > So for "hpet=force" on old ICH, allow HPET clockevents, > but do not allow HPET as a clocksource. > > http://bugzilla.kernel.org/show_bug.cgi?id=13087 > > Signed-off-by: Len Brown <len.brown@intel.com> > --- > Ingo/Peter/Thomas, > This regression was filed against ACPI, but the fix is under x86. > I'd wait for Venki's ack on anything related to HPET, > and I can send via your tree or yours, just let me know. Looks good, thanks! There's two minor details which you or Venki might want to fix when this is resubmitted with Venki's ack: > + if (hpet_is_forced_old_ich()) { > + printk(KERN_WARNING "hpet: hpet=force on old ICH enables clockevents," > + " but not clocksource.\n"); > + return -ENODEV; that should be in a single line, to make git grep work when someone greps for a line out of a syslog: git grep "hpet: hpet=force on old ICH enables clockevents, but not clocksource." ( The string can be shortened to fit nicely in a line, and/or defined separately or checkpatch can be ignored. ) > +++ b/arch/x86/kernel/quirks.c > @@ -253,6 +253,10 @@ static void old_ich_force_enable_hpet(struct pci_dev *dev) > dev_printk(KERN_DEBUG, &dev->dev, "Failed to force enable HPET\n"); > } > > +int hpet_is_forced_old_ich() { > + return (force_hpet_resume_type == OLD_ICH_FORCE_HPET_RESUME); > +} the function needs a proper prototype and the curly brace should start on the next line i guess. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Ingo, Thanks for the reply. But please disregard that patch -- we've cooked up a better one that allows ICH4M to continue to use hpet=force, even for clocksource. (and it is an ACPI patch rather than an x86 patch:-) However, I'll also send a 2nd patch to stop soliciting more hpet=force users, since technically we shouldn't be encouraging the use of this un-documented and lightly-validated hardware. thanks, Len Brown, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
* Len Brown <lenb@kernel.org> wrote: > Ingo, > Thanks for the reply. > > But please disregard that patch -- we've cooked up a better one > that allows ICH4M to continue to use hpet=force, even for clocksource. > (and it is an ACPI patch rather than an x86 patch:-) ok. > However, I'll also send a 2nd patch to stop soliciting more > hpet=force users, since technically we shouldn't be encouraging > the use of this un-documented and lightly-validated hardware. agreed - i've applied this patch. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/hpet.h b/arch/x86/include/asm/hpet.h index 1c22cb0..39d4e86 100644 --- a/arch/x86/include/asm/hpet.h +++ b/arch/x86/include/asm/hpet.h @@ -66,6 +66,7 @@ extern unsigned long hpet_address; extern unsigned long force_hpet_address; extern int hpet_force_user; +extern int hpet_is_forced_old_ich(void); extern int is_hpet_enabled(void); extern int hpet_enable(void); extern void hpet_disable(void); diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 3f0019e..8b061c7 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -752,6 +752,11 @@ static int hpet_clocksource_register(void) u64 start, now; cycle_t t1; + if (hpet_is_forced_old_ich()) { + printk(KERN_WARNING "hpet: hpet=force on old ICH enables clockevents," + " but not clocksource.\n"); + return -ENODEV; + } /* Start the counter */ hpet_restart_counter(); diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c index e95022e..9e4d73d 100644 --- a/arch/x86/kernel/quirks.c +++ b/arch/x86/kernel/quirks.c @@ -253,6 +253,10 @@ static void old_ich_force_enable_hpet(struct pci_dev *dev) dev_printk(KERN_DEBUG, &dev->dev, "Failed to force enable HPET\n"); } +int hpet_is_forced_old_ich() { + return (force_hpet_resume_type == OLD_ICH_FORCE_HPET_RESUME); +} + /* * Undocumented chipset features. Make sure that the user enforced * this.