pmaports/device/testing/linux-valve-jupiter/0014-x86-don-t-check-for-random-warps-if-using-direct-syn.patch
Clayton Craft 46bf4695d7
linux-valve-jupiter: new aport (MR 4885)
There are some important platform drivers that Valve has not upstreamed,
that are basically required for this device to operate well. I picked
those patches from the kernel tree they released for 6.5, and rebased
them onto 6.8.
2024-03-11 10:30:25 -07:00

31 lines
1.2 KiB
Diff

From 609d68f2225d5e394a573ffe9c77c82b30ea8e9d Mon Sep 17 00:00:00 2001
From: Steven Noonan <steven@uplinklabs.net>
Date: Wed, 17 Nov 2021 19:42:32 -0800
Subject: [PATCH 14/21] x86: don't check for random warps if using direct sync
There's some overhead in writing/reading MSR_IA32_TSC. We try to account
for it, but sometimes it under or over estimates the overhead, and we retry
syncing, and it sees the clock "go backwards".
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
arch/x86/kernel/tsc_sync.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 5a553feaef76..2a09a55136f4 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -400,7 +400,7 @@ static void check_tsc_sync_source(void *__cpu)
pr_debug("TSC synchronization [CPU#%d -> CPU#%u]: passed\n",
smp_processor_id(), cpu);
- } else if (atomic_dec_and_test(&test_runs) || random_warps) {
+ } else if (atomic_dec_and_test(&test_runs) || (random_warps && !tsc_allow_direct_sync)) {
/* Force it to 0 if random warps brought us here */
atomic_set(&test_runs, 0);
--
2.44.0