[PATCH 16/16] ARM: omap: disable cpuidle for OMAP3 platforms

Russell King - ARM Linux linux at arm.linux.org.uk
Wed Feb 8 11:41:11 EST 2012

Commit 2fd149645eb4 (ARM: OMAP2+: UART: Remove omap_uart_can_sleep and add pm_qos)
has caused a regression on OMAP3 platforms.

When the UART is trying to transmit data, if we enter a low power mode,
transmission stops, which makes serial on OMAP3 unusable - a 'dmesg'
takes five minutes to be output at 115200 baud, at a rate of around a
block of 16 characters every couple of seconds.

Unfortunately, the commit above can't be reverted because of many other
changes in this area, so this implements a dirty fix by disabling
CPU idle in the places the original commit does, irrespective of the
UART state.

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
 arch/arm/mach-omap2/cpuidle34xx.c |    2 ++
 arch/arm/mach-omap2/pm34xx.c      |    2 +-
 2 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 464cffd..1e9256c 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -259,6 +259,8 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
 	struct omap3_idle_statedata *cx;
 	int ret;
+	{ new_state_idx = drv->safe_state_index; goto select_state; }
 	 * Prevent idle completely if CAM is active.
 	 * CAM does not have wakeup capability in OMAP3.
diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index fc69875..88e95e6 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -421,7 +421,7 @@ static void omap3_pm_idle(void)
-	if (omap_irq_pending() || need_resched())
+	if (omap_irq_pending() || need_resched() || 1)
 		goto out;
 	trace_power_start(POWER_CSTATE, 1, smp_processor_id());

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