OMAP2+: disable idle early in the suspend sequence

Some bad interaction between the idle and the suspend paths has been
identified: the idle code is called during the suspend enter and exit
sequences. This could cause corruption or lock-up of resources.

The solution is to move the calls to disable_hlt at the very beginning
of the suspend sequence (ex. in omap3_pm_begin instead of
omap3_pm_prepare), and the call to enable_hlt at the very end of
the suspend sequence (ex. in omap3_pm_end instead of omap3_pm_finish).

Tested with RET and OFF on Beagle and OMAP3EVM.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

3 files changed, 6 insertions, 41 deletions

diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
index aaeea49b9bdd..aea7ced9a2ff 100644
--- a/arch/arm/mach-omap2/pm24xx.c
+++ b/arch/arm/mach-omap2/pm24xx.c
@@ -301,14 +301,8 @@ out:
 
 static int omap2_pm_begin(suspend_state_t state)
 {
-        suspend_state = state;
-        return 0;
-}
-
-static int omap2_pm_prepare(void)
-{
-        /* We cannot sleep in idle until we have resumed */
         disable_hlt();
+        suspend_state = state;
         return 0;
 }
 
@@ -349,21 +343,15 @@ static int omap2_pm_enter(suspend_state_t state)
         return ret;
 }
 
-static void omap2_pm_finish(void)
-{
-        enable_hlt();
-}
-
 static void omap2_pm_end(void)
 {
         suspend_state = PM_SUSPEND_ON;
+        enable_hlt();
 }
 
 static struct platform_suspend_ops omap_pm_ops = {
         .begin          = omap2_pm_begin,
-        .prepare        = omap2_pm_prepare,
         .enter          = omap2_pm_enter,
-        .finish         = omap2_pm_finish,
         .end            = omap2_pm_end,
         .valid          = suspend_valid_only_mem,
 };
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 648b8c50d024..5bf344a3fcf5 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -529,12 +529,6 @@ out:
 }
 
 #ifdef CONFIG_SUSPEND
-static int omap3_pm_prepare(void)
-{
-        disable_hlt();
-        return 0;
-}
-
 static int omap3_pm_suspend(void)
 {
         struct power_state *pwrst;
@@ -597,14 +591,10 @@ static int omap3_pm_enter(suspend_state_t unused)
         return ret;
 }
 
-static void omap3_pm_finish(void)
-{
-        enable_hlt();
-}
-
 /* Hooks to enable / disable UART interrupts during suspend */
 static int omap3_pm_begin(suspend_state_t state)
 {
+        disable_hlt();
         suspend_state = state;
         omap_uart_enable_irqs(0);
         return 0;
@@ -614,15 +604,14 @@ static void omap3_pm_end(void)
 {
         suspend_state = PM_SUSPEND_ON;
         omap_uart_enable_irqs(1);
+        enable_hlt();
         return;
 }
 
 static struct platform_suspend_ops omap_pm_ops = {
         .begin          = omap3_pm_begin,
         .end            = omap3_pm_end,
-        .prepare        = omap3_pm_prepare,
         .enter          = omap3_pm_enter,
-        .finish         = omap3_pm_finish,
         .valid          = suspend_valid_only_mem,
 };
 #endif /* CONFIG_SUSPEND */
diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
index 54544b4fc76b..6aff9961e35d 100644
--- a/arch/arm/mach-omap2/pm44xx.c
+++ b/arch/arm/mach-omap2/pm44xx.c
@@ -31,12 +31,6 @@ struct power_state {
 static LIST_HEAD(pwrst_list);
 
 #ifdef CONFIG_SUSPEND
-static int omap4_pm_prepare(void)
-{
-        disable_hlt();
-        return 0;
-}
-
 static int omap4_pm_suspend(void)
 {
         do_wfi();
@@ -59,28 +53,22 @@ static int omap4_pm_enter(suspend_state_t suspend_state)
         return ret;
 }
 
-static void omap4_pm_finish(void)
-{
-        enable_hlt();
-        return;
-}
-
 static int omap4_pm_begin(suspend_state_t state)
 {
+        disable_hlt();
         return 0;
 }
 
 static void omap4_pm_end(void)
 {
+        enable_hlt();
         return;
 }
 
 static struct platform_suspend_ops omap_pm_ops = {
         .begin          = omap4_pm_begin,
         .end            = omap4_pm_end,
-        .prepare        = omap4_pm_prepare,
         .enter          = omap4_pm_enter,
-        .finish         = omap4_pm_finish,
         .valid          = suspend_valid_only_mem,
 };
 #endif /* CONFIG_SUSPEND */