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SubjectRe: [PATCH] x86/ACPI: Fix regression caused by 16ee7b3dcc56 & c50f13c672df7
Date
On Monday, April 13, 2015 01:30:20 AM Rafael J. Wysocki wrote:
> On Sunday, April 12, 2015 11:03:30 AM Jim Bos wrote:
> > On 04/12/2015 03:29 AM, Rafael J. Wysocki wrote:
> > > On Saturday, April 11, 2015 05:08:38 PM Jim Bos wrote:
> > >> On 04/10/2015 03:56 AM, Jiang Liu wrote:
> > >>> On 2015/4/10 0:41, Jim Bos wrote:
> > >>>> On 04/09/2015 12:15 PM, Jiang Liu wrote:
> > >>>>> On 2015/4/8 23:51, Jim Bos wrote:
> > >>>>>> On 04/08/2015 07:26 AM, Jiang Liu wrote:
> > >>>>>>> On 2015/4/8 0:49, Jim Bos wrote:
> > >>>>>>>> On 04/07/2015 04:34 PM, Jiang Liu wrote:
> > >>> <snip>
> > >>>>> Hi Jim,
> > >>>>> I'm really confused. I can't even explain why my previous
> > >>>>> patch fixes the issue on AMD geode board now:(
> > >>>>>
> > >>>>> For the Dell laptop, seems you have:
> > >>>>> 1) build a kernel with Local APIC and IOAPIC enabled
> > >>>>> 2) lapic is disabled by BIOS, so there's no ACPI MADT(APIC)
> > >>>>> table at all.
> > >>>>> That means the laptop is working with 8259 PICs only.
> > >>>>> There's little change between 3.16 and 4.0 related to 8259.
> > >>>>>
> > >>>>> For the AMD geode board, I still think original code is right.
> > >>>>> I can't explain why the patch fix the issue.
> > >>>>>
> > >>>>> So could you please help to:
> > >>>>> 1) Try to enable lapic on Dell laptop in BIOS
> > >>>>> 2) Dump acpi tables and dmesg on AMD board
> > >>>>>
> > >>>>> If that still doesn't help, I will try to send you some
> > >>>>> debug patches to gather more info.
> > >>>>> Thanks!
> > >>>>> Gerry
> > >>>>>> _
> > >>>>>> Jim
> > >>>>>>
> > >>>>>
> > >>>>
> > >>>> Gerry,
> > >>>>
> > >>>> As you mentioned your patch shouldn't make a difference, run some more
> > >>>> tests, as it turns out:
> > >>>> - geode system broken on 3.16+ up to and including 3.19, however, on
> > >>>> plain 4.0-rc6 it works! Root cause appears to be there isn't an ACPI
> > >>>> interrupt assigned in non-working kernels.
> > >>>> - other system I got my hands on: Pentium(R) CPU G3220, broken on 3.19.0
> > >>>> when boot parameter 'nosmp' is specified, again no acpi entry in
> > >>>> /proc/interrupts, working fine on 4.0-rc6
> > >>>>
> > >>>> So obviously between 3.19 and 4.0-rc6 something got fixed here!
> > >>> Hi Jim,
> > >>> Yes, the bugfix patch should be:
> > >>> commit 1ea76fbadd66("x86/irq: Fix regression caused by commit b568b8601f05")
> > >>>
> > >>>> The Dell laptop remains the only problem then on 4.0-rc6, there IS an
> > >>>> acpi interrupt (but firing once apparently).
> > >>>> There isn't an option in BIOS to enable LAPIC, however, when specifying
> > >>>> 'lapic' as boot parameter I got interesting result, still not working
> > >>>> and /proc/interrups still shows XT-PIC. Doing a diff between dmesg on
> > >>>> 3.19 and 4.0-rc6 this pops out:
> > >>>>
> > >>>> -Local APIC disabled by BIOS -- you can enable it with "lapic"
> > >>>> -APIC: disable apic facility
> > >>>> -APIC: switched to apic NOOP
> > >>>> +Local APIC disabled by BIOS -- reenabling.
> > >>>> +Found and enabled local APIC!
> > >>>>
> > >>>> +Enabling APIC mode: Flat. Using 0 I/O APICs
> > >>> What's the last know working kernel for Dell laptop?
> > >>> Does it work as expected with v3.19 kernel?
> > >>> Do you means this message is from plain v4.0-rc6 kernel?
> > >>> Thanks!
> > >>> Gerry
> > >>>
> > >>>>
> > >>>> Jim
> > >>>>
> > >>>
> > >>
> > >> Gerry, Rafael,
> > >>
> > >> Ok, found it.
> > >> It was very 'interesting' bisect, because there were 2 overlapping
> > >> issues here. On the Dell laptop some kernels there wasn't an ACPI
> > >> interrupt at all or it fired once and then seemed to get stuck.
> > >> Turns out that kernel version:
> > >> 3.16: OK
> > >> 3.17: Broken (no acpi interrupt)
> > >> 3.18: actually fine
> > >> 3.19: Broken
> > >>
> > >> So started bisecting between 3.18 or 3.19, in the end found Rafael's
> > >> patch which broke it:
> > >>
> > >> ==
> > >> commit c50f13c672df758b59e026c15b9118f3ed46edc4
> > >> Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >> Date: Mon Dec 1 23:50:16 2014 +0100
> > >>
> > >> ACPICA: Save current masks of enabled GPEs after enable register writes
> > >> ==
> > >>
> > >> Reverting that patch on top of 4.0-rc7 (with some offsets and one
> > >> trivial manual edit) and I finally got a working ACPI interrupt again!
> > >
> > > That's unexpected.
> > >
> > > Is system suspend/resume involved in the reproduction of the problem in any way?
> > >
> > > In any case, does it help if you replace "enable_mask" with "enable_for_run"
> > > in line 127 of drivers/acpi/acpica/hwgpe.c (without reverting the whole commit)?
> > >
> > >
> >
> > No suspends/resumes, but this suggestion works :-)
>
> OK
>
> > --- hwgpe.c.ORIG 2015-04-12 10:41:11.754104398 +0200
> > +++ hwgpe.c 2015-04-12 10:42:38.021283593 +0200
> > @@ -124,7 +124,7 @@
> >
> > /* Only enable if the corresponding enable_mask bit is
> > set */
> >
> > - if (!(register_bit & gpe_register_info->enable_mask)) {
> > + if (!(register_bit & gpe_register_info->enable_for_run)) {
> > return (AE_BAD_PARAMETER);
> > }
> >
> > Tested-by: Jim Bos <jim876@xs4all.nl>
>
> No, no, this is not a fix. :-)
>
> It means, though, that enable_for_run and enable_mask diverge at one point and,
> moreover, enable_for_run has more bits set, which is *really* mysterious.
>
> So the only place modifying enable_for_run is acpi_ev_update_gpe_enable_mask()
> which roughly does this:
> (a) Find the register bit corresponding to the given GPE.
> (b) Clear that bit in enable_for_run.
> (c) If runtime_count is set for the GPE, set that bit in enable_for_run.
> Thus the only case when a bit may be set in enable_for_run is when runtime_count
> is nonzero for the GPE in acpi_ev_update_gpe_enable_mask().
>
> Now, acpi_ev_update_gpe_enable_mask() is only called from two places,
> acpi_ev_add_gpe_reference() and acpi_ev_remove_gpe_reference(). The former
> calls it when runtime_count has just been incremented and is now equal to one
> and the latter calls it when runtime_count has just been decremented and is now
> equal to zero. Hence, if all of the involved functions return AE_OK,
> acpi_ev_add_gpe_reference() may set the corresponding bit in enable_for_run
> and acpi_ev_remove_gpe_reference() may clear it.
>
> Further, having set the bit in enable_for_run, acpi_ev_add_gpe_reference() calls
> acpi_ev_enable_gpe() which then calls acpi_hw_low_set_gpe() with ACPI_GPE_SAVE_MASK
> set in the second argument. Again, this causes the corresponding bit to be set in
> the register's enable_mask, unless any errors are returned. In that case the
> bit will be set in both enable_for_run and enable_mask and analogously for
> acpi_ev_remove_gpe_reference(). So if I'm not overlooking anything and if all of
> the involved calls are successful, enable_for_run and enable_mask will always be
> in sync.
>
> As far as I can say that may change *only* if there's an error, because in that
> case (1) we may not save the mask that we attempted to write to the register and
> (2) we will reset runtime_count *without* updating enable_for_run which arguably
> is a bug. So the previous patch might just work accidentally.
>
> If that theory holds any water, the patch below may help too (instead of the
> previous one), so please test it. If it doesn't help, we'll need to find out
> what exactly happens on that system, but surely it is *not* usual behavior.

Actually, the one below is better, so please test this one instead.

---
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Subject: ACPICA: Store GPE register enable masks upfront

It is reported that ACPI interrupts do not work any more on
Dell Latitude D600 after commit c50f13c672df (ACPICA: Save
current masks of enabled GPEs after enable register writes).
The problem turns out to be related to the fact that the
enable_mask and enable_for_run GPE bit masks are not in
sync (in the absence of any system suspend/resume events)
for at least one GPE register on that machine.

Address this problem by writing the enable_for_run mask into
enable_mask as soon as enable_for_run is updated instead of
doing that only after the subsequent register write has
succeeded. For consistency, update acpi_hw_gpe_enable_write()
to store the bit mask to be written into the GPE register
in enable_mask unconditionally before the write.

Since the ACPI_GPE_SAVE_MASK flag is not necessary any more after
that, drop it along with the symbols depending on it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/acpica/evgpe.c | 5 +++--
drivers/acpi/acpica/hwgpe.c | 11 ++++-------
include/acpi/actypes.h | 4 ----
3 files changed, 7 insertions(+), 13 deletions(-)

Index: linux-pm/drivers/acpi/acpica/hwgpe.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpica/hwgpe.c
+++ linux-pm/drivers/acpi/acpica/hwgpe.c
@@ -89,6 +89,8 @@ u32 acpi_hw_get_gpe_register_bit(struct
* RETURN: Status
*
* DESCRIPTION: Enable or disable a single GPE in the parent enable register.
+ * The enable_mask field of the involved GPE register structure
+ * must be updated by the caller if necessary.
*
******************************************************************************/

@@ -119,7 +121,7 @@ acpi_hw_low_set_gpe(struct acpi_gpe_even
/* Set or clear just the bit that corresponds to this GPE */

register_bit = acpi_hw_get_gpe_register_bit(gpe_event_info);
- switch (action & ~ACPI_GPE_SAVE_MASK) {
+ switch (action) {
case ACPI_GPE_CONDITIONAL_ENABLE:

/* Only enable if the corresponding enable_mask bit is set */
@@ -149,9 +151,6 @@ acpi_hw_low_set_gpe(struct acpi_gpe_even
/* Write the updated enable mask */

status = acpi_hw_write(enable_mask, &gpe_register_info->enable_address);
- if (ACPI_SUCCESS(status) && (action & ACPI_GPE_SAVE_MASK)) {
- gpe_register_info->enable_mask = (u8)enable_mask;
- }
return (status);
}

@@ -286,10 +285,8 @@ acpi_hw_gpe_enable_write(u8 enable_mask,
{
acpi_status status;

+ gpe_register_info->enable_mask = enable_mask;
status = acpi_hw_write(enable_mask, &gpe_register_info->enable_address);
- if (ACPI_SUCCESS(status)) {
- gpe_register_info->enable_mask = enable_mask;
- }
return (status);
}

Index: linux-pm/include/acpi/actypes.h
===================================================================
--- linux-pm.orig/include/acpi/actypes.h
+++ linux-pm/include/acpi/actypes.h
@@ -736,10 +736,6 @@ typedef u32 acpi_event_status;
#define ACPI_GPE_ENABLE 0
#define ACPI_GPE_DISABLE 1
#define ACPI_GPE_CONDITIONAL_ENABLE 2
-#define ACPI_GPE_SAVE_MASK 4
-
-#define ACPI_GPE_ENABLE_SAVE (ACPI_GPE_ENABLE | ACPI_GPE_SAVE_MASK)
-#define ACPI_GPE_DISABLE_SAVE (ACPI_GPE_DISABLE | ACPI_GPE_SAVE_MASK)

/*
* GPE info flags - Per GPE
Index: linux-pm/drivers/acpi/acpica/evgpe.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpica/evgpe.c
+++ linux-pm/drivers/acpi/acpica/evgpe.c
@@ -92,6 +92,7 @@ acpi_ev_update_gpe_enable_mask(struct ac
ACPI_SET_BIT(gpe_register_info->enable_for_run,
(u8)register_bit);
}
+ gpe_register_info->enable_mask = gpe_register_info->enable_for_run;

return_ACPI_STATUS(AE_OK);
}
@@ -123,7 +124,7 @@ acpi_status acpi_ev_enable_gpe(struct ac

/* Enable the requested GPE */

- status = acpi_hw_low_set_gpe(gpe_event_info, ACPI_GPE_ENABLE_SAVE);
+ status = acpi_hw_low_set_gpe(gpe_event_info, ACPI_GPE_ENABLE);
return_ACPI_STATUS(status);
}

@@ -202,7 +203,7 @@ acpi_ev_remove_gpe_reference(struct acpi
if (ACPI_SUCCESS(status)) {
status =
acpi_hw_low_set_gpe(gpe_event_info,
- ACPI_GPE_DISABLE_SAVE);
+ ACPI_GPE_DISABLE);
}

if (ACPI_FAILURE(status)) {


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