[PATCH 1/2] OMAP3: cpuidle: prevent CORE power domain from going to RET or OFF when DSS is on

[Paul Walmsley]

From: Tero Kristo <tero.kristo at nokia.com>

Prevent the CORE power domain from entering RETENTION or OFF when DSS
is on.  Otherwise, the display FIFO(s) may underflow due to the time
needed for the CORE to wake back up, causing tearing and unnecessary
interrupts.

Signed-off-by: Tero Kristo <tero.kristo at nokia.com>
[paul at pwsan.com: wrote commit message]
Signed-off-by: Paul Walmsley <paul at pwsan.com>
---
 arch/arm/mach-omap2/cpuidle34xx.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 0335cd8..d1b7789 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -9,8 +9,9 @@
  * Copyright (C) 2007 Texas Instruments, Inc.
  * Karthik Dasu <karthik-dp at ti.com>
  *
- * Copyright (C) 2006 Nokia Corporation
+ * Copyright (C) 2006, 2011 Nokia Corporation
  * Tony Lindgren <tony at atomide.com>
+ * Tero Kristo <tero.kristo at nokia.com>
  *
  * Copyright (C) 2005 Texas Instruments, Inc.
  * Richard Woodruff <r-woodruff2 at ti.com>
@@ -268,6 +269,12 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
 		goto select_state;
 	}
 
+	/* If DSS is active, prevent CORE RET/OFF */
+	dss_state = pwrdm_read_pwrst(dss_pd);
+	if (dss_state == PWRDM_POWER_ON &&
+	    core_next_state != PWRDM_POWER_ON)
+		core_next_state = PWRDM_POWER_INACTIVE;
+
 	/*
 	 * Prevent PER off if CORE is not in retention or off as this
 	 * would disable PER wakeups completely.
@@ -288,7 +295,6 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev,
 		iva2_state = pwrdm_read_pwrst(iva2_pd);
 		sgx_state = pwrdm_read_pwrst(sgx_pd);
 		usb_state = pwrdm_read_pwrst(usb_pd);
-		dss_state = pwrdm_read_pwrst(dss_pd);
 
 		if (cam_state > PWRDM_POWER_OFF ||
 		    dss_state > PWRDM_POWER_OFF ||