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Commit 0213df74 authored by Dave Jones's avatar Dave Jones Committed by Linus Torvalds
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[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: default avatarMark Langsdorf <mark.langsdorf@amd.com>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3078fcc1

arch/i386/kernel/cpu/cpufreq/powernow-k8.c

+19 −11
Original line number Original line Diff line number Diff line
@@ -44,7 +44,7 @@ 




#define PFX "powernow-k8: "

#define PFX "powernow-k8: "

#define BFX PFX "BIOS error: "

#define BFX PFX "BIOS error: "

#define VERSION "version 1.50.3"

#define VERSION "version 1.50.4"

#include "powernow-k8.h"

#include "powernow-k8.h"





/* serialize freq changes  */

/* serialize freq changes  */
@@ -111,8 +111,8 @@ static int query_current_values_with_pending_wait(struct powernow_k8_data *data) 
	u32 i = 0;

	u32 i = 0;





	do {

	do {

		if (i++ > 0x1000000) {

		if (i++ > 10000) {

			printk(KERN_ERR PFX "detected change pending stuck\n");

			dprintk("detected change pending stuck\n");

			return 1;

			return 1;

		}

		}

		rdmsr(MSR_FIDVID_STATUS, lo, hi);

		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 lo;

	u32 savevid = data->currvid;

	u32 savevid = data->currvid;

	u32 i = 0;





	if ((fid & INVALID_FID_MASK) || (data->currvid & INVALID_VID_MASK)) {

	if ((fid & INVALID_FID_MASK) || (data->currvid & INVALID_VID_MASK)) {

		printk(KERN_ERR PFX "internal error - overflow on fid write\n");

		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",

	dprintk("writing fid 0x%x, lo 0x%x, hi 0x%x\n",

		fid, lo, data->plllock * PLL_LOCK_CONVERSION);

		fid, lo, data->plllock * PLL_LOCK_CONVERSION);





	do {

		wrmsr(MSR_FIDVID_CTL, lo, data->plllock * PLL_LOCK_CONVERSION);

		wrmsr(MSR_FIDVID_CTL, lo, data->plllock * PLL_LOCK_CONVERSION);



		if (i++ > 100) {

	if (query_current_values_with_pending_wait(data))

			printk(KERN_ERR PFX "internal error - pending bit very stuck - no further pstate changes possible\n");

		return 1;

			retrun 1;

		}			

	} while (query_current_values_with_pending_wait(data));





	count_off_irt(data);

	count_off_irt(data);
@@ -197,6 +201,7 @@ static int write_new_vid(struct powernow_k8_data *data, u32 vid) 
{

{

	u32 lo;

	u32 lo;

	u32 savefid = data->currfid;

	u32 savefid = data->currfid;

	int i = 0;





	if ((data->currfid & INVALID_FID_MASK) || (vid & INVALID_VID_MASK)) {

	if ((data->currfid & INVALID_FID_MASK) || (vid & INVALID_VID_MASK)) {

		printk(KERN_ERR PFX "internal error - overflow on vid write\n");

		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",

	dprintk("writing vid 0x%x, lo 0x%x, hi 0x%x\n",

		vid, lo, STOP_GRANT_5NS);

		vid, lo, STOP_GRANT_5NS);





	do {

		wrmsr(MSR_FIDVID_CTL, lo, STOP_GRANT_5NS);

		wrmsr(MSR_FIDVID_CTL, lo, STOP_GRANT_5NS);



                if (i++ > 100) {

	if (query_current_values_with_pending_wait(data))

                        printk(KERN_ERR PFX "internal error - pending bit very stuck - no further pstate changes possible\n");

                        return 1;

                        return 1;

                }

	} while (query_current_values_with_pending_wait(data));





	if (savefid != data->currfid) {

	if (savefid != data->currfid) {

		printk(KERN_ERR PFX "fid changed on vid trans, old 0x%x new 0x%x\n",

		printk(KERN_ERR PFX "fid changed on vid trans, old 0x%x new 0x%x\n",