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Merge d58db3f3a0 ("Merge tag 'docs-6.12' of git://git.lwn.net/linux") into android-mainline

Browse Source 
Steps on the way to 6.12-rc1

Bug: 367265496
Change-Id: If60ec1a650903bc7f1e176954ae2cc19590f580c
Signed-off-by: Matthias Maennich <maennich@google.com>
This commit is contained in:
Matthias Maennich
2024-09-25 09:06:53 +00:00
parent 16b2568505 d58db3f3a0
commit 8ab8a434ea
156 changed files with 3829 additions and 1546 deletions
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drivers/clocksource/i8253.c
+36 -17
View File
@@ -20,13 +20,6 @@
DEFINE_RAW_SPINLOCK(i8253_lock);
EXPORT_SYMBOL(i8253_lock);
/*
* Handle PIT quirk in pit_shutdown() where zeroing the counter register
* restarts the PIT, negating the shutdown. On platforms with the quirk,
* platform specific code can set this to false.
*/
bool i8253_clear_counter_on_shutdown __ro_after_init = true;
#ifdef CONFIG_CLKSRC_I8253
/*
* Since the PIT overflows every tick, its not very useful
@@ -108,21 +101,47 @@ int __init clocksource_i8253_init(void)
#endif
#ifdef CONFIG_CLKEVT_I8253
void clockevent_i8253_disable(void)
{
raw_spin_lock(&i8253_lock);
/*
* Writing the MODE register should stop the counter, according to
* the datasheet. This appears to work on real hardware (well, on
* modern Intel and AMD boxes; I didn't dig the Pegasos out of the
* shed).
*
* However, some virtual implementations differ, and the MODE change
* doesn't have any effect until either the counter is written (KVM
* in-kernel PIT) or the next interrupt (QEMU). And in those cases,
* it may not stop the *count*, only the interrupts. Although in
* the virt case, that probably doesn't matter, as the value of the
* counter will only be calculated on demand if the guest reads it;
* it's the interrupts which cause steal time.
*
* Hyper-V apparently has a bug where even in mode 0, the IRQ keeps
* firing repeatedly if the counter is running. But it *does* do the
* right thing when the MODE register is written.
*
* So: write the MODE and then load the counter, which ensures that
* the IRQ is stopped on those buggy virt implementations. And then
* write the MODE again, which is the right way to stop it.
*/
outb_p(0x30, PIT_MODE);
outb_p(0, PIT_CH0);
outb_p(0, PIT_CH0);
outb_p(0x30, PIT_MODE);
raw_spin_unlock(&i8253_lock);
}
static int pit_shutdown(struct clock_event_device *evt)
{
if (!clockevent_state_oneshot(evt) && !clockevent_state_periodic(evt))
return 0;
raw_spin_lock(&i8253_lock);
outb_p(0x30, PIT_MODE);
if (i8253_clear_counter_on_shutdown) {
outb_p(0, PIT_CH0);
outb_p(0, PIT_CH0);
}
raw_spin_unlock(&i8253_lock);
clockevent_i8253_disable();
return 0;
}