From 0213df74315bbab9ccaa73146f3e11972ea6de46 Mon Sep 17 00:00:00 2001 From: Dave Jones Date: Fri, 21 Oct 2005 17:21:03 -0400 Subject: [PATCH] [PATCH] cpufreq: fix pending powernow timer stuck condition AMD recently discovered that on some hardware, there is a race condition possible when a C-state change request goes onto the bus at the same time as a P-state change request. Both requests happen, but the southbridge hardware only acknowledges the C-state change. The PowerNow! driver is then stuck in a loop, waiting for the P-state change acknowledgement. The driver eventually times out, but can no longer perform P-state changes. It turns out the solution is to resend the P-state change, which the southbridge will acknowledge normally. Thanks to Johannes Winkelmann for reporting this and testing the fix. Signed-off-by: Mark Langsdorf Signed-off-by: Dave Jones Signed-off-by: Linus Torvalds --- arch/i386/kernel/cpu/cpufreq/powernow-k8.c | 30 ++++++++++++++-------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/arch/i386/kernel/cpu/cpufreq/powernow-k8.c b/arch/i386/kernel/cpu/cpufreq/powernow-k8.c index ab6e0611303d..ec3a9e335aa3 100644 --- a/arch/i386/kernel/cpu/cpufreq/powernow-k8.c +++ b/arch/i386/kernel/cpu/cpufreq/powernow-k8.c @@ -44,7 +44,7 @@ #define PFX "powernow-k8: " #define BFX PFX "BIOS error: " -#define VERSION "version 1.50.3" +#define VERSION "version 1.50.4" #include "powernow-k8.h" /* serialize freq changes */ @@ -111,8 +111,8 @@ static int query_current_values_with_pending_wait(struct powernow_k8_data *data) u32 i = 0; do { - if (i++ > 0x1000000) { - printk(KERN_ERR PFX "detected change pending stuck\n"); + if (i++ > 10000) { + dprintk("detected change pending stuck\n"); return 1; } rdmsr(MSR_FIDVID_STATUS, lo, hi); @@ -159,6 +159,7 @@ static int write_new_fid(struct powernow_k8_data *data, u32 fid) { u32 lo; u32 savevid = data->currvid; + u32 i = 0; if ((fid & INVALID_FID_MASK) || (data->currvid & INVALID_VID_MASK)) { printk(KERN_ERR PFX "internal error - overflow on fid write\n"); @@ -170,10 +171,13 @@ static int write_new_fid(struct powernow_k8_data *data, u32 fid) dprintk("writing fid 0x%x, lo 0x%x, hi 0x%x\n", fid, lo, data->plllock * PLL_LOCK_CONVERSION); - wrmsr(MSR_FIDVID_CTL, lo, data->plllock * PLL_LOCK_CONVERSION); - - if (query_current_values_with_pending_wait(data)) - return 1; + do { + wrmsr(MSR_FIDVID_CTL, lo, data->plllock * PLL_LOCK_CONVERSION); + if (i++ > 100) { + printk(KERN_ERR PFX "internal error - pending bit very stuck - no further pstate changes possible\n"); + retrun 1; + } + } while (query_current_values_with_pending_wait(data)); count_off_irt(data); @@ -197,6 +201,7 @@ static int write_new_vid(struct powernow_k8_data *data, u32 vid) { u32 lo; u32 savefid = data->currfid; + int i = 0; if ((data->currfid & INVALID_FID_MASK) || (vid & INVALID_VID_MASK)) { printk(KERN_ERR PFX "internal error - overflow on vid write\n"); @@ -208,10 +213,13 @@ static int write_new_vid(struct powernow_k8_data *data, u32 vid) dprintk("writing vid 0x%x, lo 0x%x, hi 0x%x\n", vid, lo, STOP_GRANT_5NS); - wrmsr(MSR_FIDVID_CTL, lo, STOP_GRANT_5NS); - - if (query_current_values_with_pending_wait(data)) - return 1; + do { + wrmsr(MSR_FIDVID_CTL, lo, STOP_GRANT_5NS); + if (i++ > 100) { + printk(KERN_ERR PFX "internal error - pending bit very stuck - no further pstate changes possible\n"); + return 1; + } + } while (query_current_values_with_pending_wait(data)); if (savefid != data->currfid) { printk(KERN_ERR PFX "fid changed on vid trans, old 0x%x new 0x%x\n",