Attachment 56705 Details for Bug 103786

[patch] Retry to Pstate change request until they are successful

pn-collision-retry.patch (text/plain), 2.85 KB, created by Thomas Renninger on 2005-11-08 16:43:29 UTC

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Creator: Thomas Renninger

Created: 2005-11-08 16:43:29 UTC

Size: 2.85 KB

patch

obsolete

>Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
>
>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.
>
>--- linux-2.6.13.4/arch/i386/kernel/cpu/cpufreq/powernow-k8.c	2005-10-21 14:39:50.000000000 -0500
>+++ linux-revamp/arch/i386/kernel/cpu/cpufreq/powernow-k8-2.c	2005-10-21 14:30:25.000000000 -0500
>@@ -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 @@
> 	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 @@
> {
> 	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 @@
> 	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 @@
> {
> 	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 @@
> 	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",

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