ARM:OMAP2: an issue about curr_pwrst, u8 is never < 0

if pwrdm_read_pwrst returns negative number, curr_pwrst can not notice it. since really need check curr_pwrst whether is negative,
need let the check valid in _pwrdm_save_clkdm_state_and_activate. and also better to check the return value of pwrdm_read_pwrst, firstly.

Signed-off-by Chen Gang <[email protected]>

Hi,

Quoted 6 lines · Chen Gang

if pwrdm_read_pwrst returns negative number, curr_pwrst can not notice it. since really need check curr_pwrst whether is negative,
need let the check valid in _pwrdm_save_clkdm_state_and_activate. and also better to check the return value of pwrdm_read_pwrst, firstly.

Quoted 1 line

Signed-off-by Chen Gang <[email protected]>

thanks for reporting this and sending a suggested fix. The following patch is what I've queued here, which should deal with the root cause without the casts.

- Paul

From: Paul Walmsley <[email protected]>
Date: Sun, 31 Mar 2013 20:22:22 -0600
Subject: [PATCH] ARM: OMAP2+: powerdomain: avoid testing whether an unsigned
char is less than 0

_pwrdm_save_clkdm_state_and_activate() tried to test one of its unsigned arguments to determine whether it was less than zero. Fix by moving the error test to the caller.

Reported-by Chen Gang <[email protected]>

Signed-off-by Paul Walmsley <[email protected]>

---
 arch/arm/mach-omap2/powerdomain.c |   18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

arch/arm/mach-omap2/powerdomain.c +8 -10

index 8e61d80..89cad4a 100644
@@ -52,7 +52,6 @@ enum {
 #define ALREADYACTIVE_SWITCH		0
 #define FORCEWAKEUP_SWITCH		1
 #define LOWPOWERSTATE_SWITCH		2
-#define ERROR_SWITCH			3
 
 /* pwrdm_list contains all registered struct powerdomains */
 static LIST_HEAD(pwrdm_list);

@@ -233,10 +232,7 @@ static u8 _pwrdm_save_clkdm_state_and_activate(struct powerdomain *pwrdm,
 {
 	u8 sleep_switch;
 
-	if (curr_pwrst < 0) {
-		WARN_ON(1);
-		sleep_switch = ERROR_SWITCH;
-	} else if (curr_pwrst < PWRDM_POWER_ON) {
+	if (curr_pwrst < PWRDM_POWER_ON) {
 		if (curr_pwrst > pwrst &&
 		    pwrdm->flags & PWRDM_HAS_LOWPOWERSTATECHANGE &&
 		    arch_pwrdm->pwrdm_set_lowpwrstchange) {

@@ -1091,7 +1087,8 @@ int pwrdm_post_transition(struct powerdomain *pwrdm)
  */
 int omap_set_pwrdm_state(struct powerdomain *pwrdm, u8 pwrst)
 {
-	u8 curr_pwrst, next_pwrst, sleep_switch;
+	u8 next_pwrst, sleep_switch;
+	int curr_pwrst;
 	int ret = 0;
 	bool hwsup = false;
 

@@ -1107,16 +1104,17 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm, u8 pwrst)
 	pwrdm_lock(pwrdm);
 
 	curr_pwrst = pwrdm_read_pwrst(pwrdm);
+	if (curr_pwrst < 0) {
+		ret = -EINVAL;
+		goto osps_out;
+	}
+
 	next_pwrst = pwrdm_read_next_pwrst(pwrdm);
 	if (curr_pwrst == pwrst && next_pwrst == pwrst)
 		goto osps_out;
 
 	sleep_switch = _pwrdm_save_clkdm_state_and_activate(pwrdm, curr_pwrst,
 							    pwrst, &hwsup);
-	if (sleep_switch == ERROR_SWITCH) {
-		ret = -EINVAL;
-		goto osps_out;
-	}
 
 	ret = pwrdm_set_next_pwrst(pwrdm, pwrst);
 	if (ret)