Patch "ARM: omap2+: am437x: rollback to use omap3_gptimer_timer_init()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

ARM: omap2+: am437x: rollback to use omap3_gptimer_timer_init()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-omap2-am437x-rollback-to-use-omap3_gptimer_timer_init.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Grygorii Strashko <[email protected]>
Date: Mon, 5 Dec 2016 09:27:44 +0530
Subject: ARM: omap2+: am437x: rollback to use omap3_gptimer_timer_init()

From: Grygorii Strashko <[email protected]>

commit f86a2c875fd146d9b82c8fdd86d31084507bcf4c upstream.

The commit 55ee7017ee31 ("arm: omap2: board-generic: use omap4_local_timer_init for AM437x") unintentionally changes the clocksource devices for AM437x from OMAP GP Timer to SyncTimer32K.

Unfortunately, the SyncTimer32K is starving from frequency deviation as mentioned in commit 5b5c01359152 ("ARM: OMAP2+: AM43x: Use gptimer as clocksource") and, as reported by Franklin [1], even its monotonic nature is under question (most probably there is a HW issue, but it's still under investigation).

Taking into account above facts It's reasonable to rollback to the use of omap3_gptimer_timer_init().

[1] http://www.spinics.net/lists/linux-omap/msg127425.html

omap4_local_timer_init for AM437x")

---
 arch/arm/mach-omap2/board-generic.c |    2 +-
 arch/arm/mach-omap2/timer.c         |    9 +++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

@@ -306,7 +306,7 @@ DT_MACHINE_START(AM43_DT, "Generic AM43
 	.init_late	= am43xx_init_late,
 	.init_irq	= omap_gic_of_init,
 	.init_machine	= omap_generic_init,
-	.init_time	= omap4_local_timer_init,
+	.init_time	= omap3_gptimer_timer_init,
 	.dt_compat	= am43_boards_compat,
 	.restart	= omap44xx_restart,
 MACHINE_END

@@ -510,18 +510,19 @@ void __init omap3_secure_sync32k_timer_i
 }
 #endif /* CONFIG_ARCH_OMAP3 */
 
-#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX)
+#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) || \
+	defined(CONFIG_SOC_AM43XX)
 void __init omap3_gptimer_timer_init(void)
 {
 	__omap_sync32k_timer_init(2, "timer_sys_ck", NULL,
 			1, "timer_sys_ck", "ti,timer-alwon", true);
-
-	clocksource_probe();
+	if (of_have_populated_dt())
+		clocksource_probe();
 }
 #endif
 
 #if defined(CONFIG_ARCH_OMAP4) || defined(CONFIG_SOC_OMAP5) ||		\
-	defined(CONFIG_SOC_DRA7XX) || defined(CONFIG_SOC_AM43XX)
+	defined(CONFIG_SOC_DRA7XX)
 static void __init omap4_sync32k_timer_init(void)
 {
 	__omap_sync32k_timer_init(1, "timer_32k_ck", "ti,timer-alwon",

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/arm-omap2-am437x-rollback-to-use-omap3_gptimer_timer_init.patch