From: Jan Beulich <jbeulich@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>,
"Grzegorz Uriasz" <gorbak25@gmail.com>
Cc: artur@puzio.waw.pl, Wei Liu <wl@xen.org>,
jakub@bartmin.ski, Andrew Cooper <andrew.cooper3@citrix.com>,
marmarek@invisiblethingslab.com, j.nowak26@student.uw.edu.pl,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH 1/1] x86/acpi: Use FADT flags to determine the PMTMR width
Date: Tue, 16 Jun 2020 15:25:42 +0200 [thread overview]
Message-ID: <e6356183-cabe-1c54-dc6d-04365d4650a7@suse.com> (raw)
In-Reply-To: <20200616103204.GN735@Air-de-Roger>
On 16.06.2020 12:32, Roger Pau Monné wrote:
> On Tue, Jun 16, 2020 at 10:07:05AM +0200, Jan Beulich wrote:
>> On 14.06.2020 16:36, Grzegorz Uriasz wrote:
>>> --- a/xen/arch/x86/acpi/boot.c
>>> +++ b/xen/arch/x86/acpi/boot.c
>>> @@ -480,7 +480,10 @@ static int __init acpi_parse_fadt(struct acpi_table_header *table)
>>> if (fadt->xpm_timer_block.space_id ==
>>> ACPI_ADR_SPACE_SYSTEM_IO) {
>>> pmtmr_ioport = fadt->xpm_timer_block.address;
>>> - pmtmr_width = fadt->xpm_timer_block.bit_width;
>>> + if (fadt->flags & ACPI_FADT_32BIT_TIMER)
>>> + pmtmr_width = 32;
>>> + else
>>> + pmtmr_width = 24;
>>
>> I think disagreement of the two wants logging, and you want to
>> default to using the smaller of the two (or even to ignoring the
>> timer altogether). Then there wants to be a way to override
>> (unless we already have one) our defaulting, in case it's wrong.
>
> TBH, I presume timer_block will always return 32bits, because that's
> the size of the register. Then the timer can implement less bits than
> the full size of the register, and that's what gets signaled using the
> ACPI flags. What we care about here is the number of bits used by the
> timer, not the size of the register.
>
> I think we should only ignore the timer if pm_timer_block.bit_width <
> pmtmr_width.
>
> Printing a (debug) message when those values disagree is fine, but I
> bet it's going to trigger always when the implemented timer is only
> using 24bits.
The 2nd system I tried on would trigger it, so maybe there's no point
in logging indeed. How about the below as a basis?
Jan
--- unstable.orig/xen/arch/x86/acpi/boot.c
+++ unstable/xen/arch/x86/acpi/boot.c
@@ -480,7 +480,9 @@ static int __init acpi_parse_fadt(struct
if (fadt->header.revision >= FADT2_REVISION_ID) {
/* FADT rev. 2 */
if (fadt->xpm_timer_block.space_id ==
- ACPI_ADR_SPACE_SYSTEM_IO) {
+ ACPI_ADR_SPACE_SYSTEM_IO &&
+ (fadt->xpm_timer_block.access_width == 0 ||
+ fadt->xpm_timer_block.access_width == 3)) {
pmtmr_ioport = fadt->xpm_timer_block.address;
pmtmr_width = fadt->xpm_timer_block.bit_width;
}
@@ -492,8 +494,10 @@ static int __init acpi_parse_fadt(struct
*/
if (!pmtmr_ioport) {
pmtmr_ioport = fadt->pm_timer_block;
- pmtmr_width = fadt->pm_timer_length == 4 ? 24 : 0;
+ pmtmr_width = fadt->pm_timer_length == 4 ? 32 : 0;
}
+ if (pmtmr_width > 24 && !(fadt->flags & ACPI_FADT_32BIT_TIMER))
+ pmtmr_width = 24;
if (pmtmr_ioport)
printk(KERN_INFO PREFIX "PM-Timer IO Port: %#x (%u bits)\n",
pmtmr_ioport, pmtmr_width);
--- unstable.orig/xen/arch/x86/time.c
+++ unstable/xen/arch/x86/time.c
@@ -465,7 +465,7 @@ static s64 __init init_pmtimer(struct pl
u64 start;
u32 count, target, mask = 0xffffff;
- if ( !pmtmr_ioport || !pmtmr_width )
+ if ( !pmtmr_ioport )
return 0;
if ( pmtmr_width == 32 )
@@ -473,6 +473,8 @@ static s64 __init init_pmtimer(struct pl
pts->counter_bits = 32;
mask = 0xffffffff;
}
+ else if ( pmtmr_width != pts->counter_bits )
+ return 0;
count = inl(pmtmr_ioport) & mask;
start = rdtsc_ordered();
next prev parent reply other threads:[~2020-06-16 13:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-14 14:36 [PATCH 0/1] Fix broken suspend on some machines Grzegorz Uriasz
2020-06-14 14:36 ` [PATCH 1/1] x86/acpi: Use FADT flags to determine the PMTMR width Grzegorz Uriasz
2020-06-15 7:05 ` Roger Pau Monné
2020-06-16 8:07 ` Jan Beulich
2020-06-16 10:32 ` Roger Pau Monné
2020-06-16 12:31 ` Jan Beulich
2020-06-16 13:25 ` Jan Beulich [this message]
2020-06-16 14:59 ` Roger Pau Monné
2020-06-16 15:10 ` Grzegorz Uriasz
2020-06-16 15:13 ` Jan Beulich
2020-06-16 15:11 ` Jan Beulich
2020-06-16 15:25 ` Roger Pau Monné
2020-06-17 6:16 ` Grzegorz Uriasz
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