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Date: Sun, 23 Feb 2014 00:59:50 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: Linus Torvalds <torvalds@...ux-foundation.org>
cc: LKML <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>
Subject: [GIT pull] x86 fixes for 3.14
Linus,
please pull the latest x86-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-for-linus
This pull request provides:
* A bugfix which prevents a divide by 0 panic when the in 3.14
newly introduced try_msr_calibrate_tsc() fails.
* The enablement of the Baytrail platform to utilize the new
fangled msr based calibration
Thanks,
tglx
------------------>
Mika Westerberg (1):
x86: tsc: Add missing Baytrail frequency to the table
Thomas Gleixner (1):
x86, tsc: Fallback to normal calibration if fast MSR calibration fails
arch/x86/include/asm/tsc.h | 2 +-
arch/x86/kernel/tsc.c | 7 ++-----
arch/x86/kernel/tsc_msr.c | 30 +++++++++++++++---------------
3 files changed, 18 insertions(+), 21 deletions(-)
diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 57ae63c..94605c0 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -66,6 +66,6 @@ extern void tsc_save_sched_clock_state(void);
extern void tsc_restore_sched_clock_state(void);
/* MSR based TSC calibration for Intel Atom SoC platforms */
-int try_msr_calibrate_tsc(unsigned long *fast_calibrate);
+unsigned long try_msr_calibrate_tsc(void);
#endif /* _ASM_X86_TSC_H */
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index acb3b60..cfbe99f 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -653,13 +653,10 @@ unsigned long native_calibrate_tsc(void)
/* Calibrate TSC using MSR for Intel Atom SoCs */
local_irq_save(flags);
- i = try_msr_calibrate_tsc(&fast_calibrate);
+ fast_calibrate = try_msr_calibrate_tsc();
local_irq_restore(flags);
- if (i >= 0) {
- if (i == 0)
- pr_warn("Fast TSC calibration using MSR failed\n");
+ if (fast_calibrate)
return fast_calibrate;
- }
local_irq_save(flags);
fast_calibrate = quick_pit_calibrate();
diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c
index 8b5434f..92ae6ac 100644
--- a/arch/x86/kernel/tsc_msr.c
+++ b/arch/x86/kernel/tsc_msr.c
@@ -53,7 +53,7 @@ static struct freq_desc freq_desc_tables[] = {
/* TNG */
{ 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } },
/* VLV2 */
- { 6, 0x37, 1, { 0, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
+ { 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
/* ANN */
{ 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } },
};
@@ -77,21 +77,18 @@ static int match_cpu(u8 family, u8 model)
/*
* Do MSR calibration only for known/supported CPUs.
- * Return values:
- * -1: CPU is unknown/unsupported for MSR based calibration
- * 0: CPU is known/supported, but calibration failed
- * 1: CPU is known/supported, and calibration succeeded
+ *
+ * Returns the calibration value or 0 if MSR calibration failed.
*/
-int try_msr_calibrate_tsc(unsigned long *fast_calibrate)
+unsigned long try_msr_calibrate_tsc(void)
{
- int cpu_index;
u32 lo, hi, ratio, freq_id, freq;
+ unsigned long res;
+ int cpu_index;
cpu_index = match_cpu(boot_cpu_data.x86, boot_cpu_data.x86_model);
if (cpu_index < 0)
- return -1;
-
- *fast_calibrate = 0;
+ return 0;
if (freq_desc_tables[cpu_index].msr_plat) {
rdmsr(MSR_PLATFORM_INFO, lo, hi);
@@ -103,7 +100,7 @@ int try_msr_calibrate_tsc(unsigned long *fast_calibrate)
pr_info("Maximum core-clock to bus-clock ratio: 0x%x\n", ratio);
if (!ratio)
- return 0;
+ goto fail;
/* Get FSB FREQ ID */
rdmsr(MSR_FSB_FREQ, lo, hi);
@@ -112,16 +109,19 @@ int try_msr_calibrate_tsc(unsigned long *fast_calibrate)
pr_info("Resolved frequency ID: %u, frequency: %u KHz\n",
freq_id, freq);
if (!freq)
- return 0;
+ goto fail;
/* TSC frequency = maximum resolved freq * maximum resolved bus ratio */
- *fast_calibrate = freq * ratio;
- pr_info("TSC runs at %lu KHz\n", *fast_calibrate);
+ res = freq * ratio;
+ pr_info("TSC runs at %lu KHz\n", res);
#ifdef CONFIG_X86_LOCAL_APIC
lapic_timer_frequency = (freq * 1000) / HZ;
pr_info("lapic_timer_frequency = %d\n", lapic_timer_frequency);
#endif
+ return res;
- return 1;
+fail:
+ pr_warn("Fast TSC calibration using MSR failed\n");
+ return 0;
}
--
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