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ARM: hwmod: RTC: Don't assume lock/unlock will be called with irq enabled

PATCH New Keerthy 2 participants 2 messages Jun 21, 2018 – Jul 3, 2018

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Arm (32-bit) Arm sub-architectures OMAP2+ support
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Keerthy

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PATCH 1/1 ARM: hwmod: RTC: Don't assume lock/unlock will be called with irq enabled

From: Dave Gerlach <[email protected]>

When the RTC lock and unlock functions were introduced it was likely assumed that they would always be called from irq enabled context, hence the use of local_irq_disable/enable. This is no longer true as the RTC+DDR path makes a late call during the suspend path after irqs have been disabled to enable the RTC hwmod which calls both unlock and lock, leading to IRQs being reenabled through the local_irq_enable call in omap_hwmod_rtc_lock call.

To avoid this change the local_irq_disable/enable to local_irq_save/restore to ensure that from whatever context this is called the proper IRQ configuration is maintained.

Signed-off-by Dave Gerlach <[email protected]>
Signed-off-by Keerthy <[email protected]>
---
 arch/arm/mach-omap2/omap_hwmod_reset.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
arch/arm/mach-omap2/omap_hwmod_reset.c +8 -4
index b68f9c0..d5ddba0 100644
@@ -92,11 +92,13 @@ static void omap_rtc_wait_not_busy(struct omap_hwmod *oh)
  */
 void omap_hwmod_rtc_unlock(struct omap_hwmod *oh)
 {
-	local_irq_disable();
+	unsigned long flags;
+
+	local_irq_save(flags);
 	omap_rtc_wait_not_busy(oh);
 	omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG);
 	omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG);
-	local_irq_enable();
+	local_irq_restore(flags);
 }
 
 /**

@@ -110,9 +112,11 @@ void omap_hwmod_rtc_unlock(struct omap_hwmod *oh)
  */
 void omap_hwmod_rtc_lock(struct omap_hwmod *oh)
 {
-	local_irq_disable();
+	unsigned long flags;
+
+	local_irq_save(flags);
 	omap_rtc_wait_not_busy(oh);
 	omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG);
 	omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG);
-	local_irq_enable();
+	local_irq_restore(flags);
 }
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#1 lore raw

PATCH 1/1 ARM: hwmod: RTC: Don't assume lock/unlock will be called with irq enabled

Quoted 10 lines · Keerthy

From: Dave Gerlach <[email protected]>

When the RTC lock and unlock functions were introduced it was likely assumed that they would always be called from irq enabled context, hence the use of local_irq_disable/enable. This is no longer true as the RTC+DDR path makes a late call during the suspend path after irqs have been disabled to enable the RTC hwmod which calls both unlock and lock, leading to IRQs being reenabled through the local_irq_enable call in omap_hwmod_rtc_lock call.

Quoted 3 lines

To avoid this change the local_irq_disable/enable to local_irq_save/restore to ensure that from whatever context this is called the proper IRQ configuration is maintained.

Thanks applying into omap-for-v4.19/soc.

Tony