1 files changed, 20 insertions, 11 deletions

diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index b9b995f8a36e..05a1547642b6 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -598,7 +598,21 @@ static int at91_suspend_finish(unsigned long val)
 	return 0;
 }
 
-static void at91_pm_switch_ba_to_vbat(void)
+/**
+ * at91_pm_switch_ba_to_auto() - Configure Backup Unit Power Switch
+ * to automatic/hardware mode.
+ *
+ * The Backup Unit Power Switch can be managed either by software or hardware.
+ * Enabling hardware mode allows the automatic transition of power between
+ * VDDANA (or VDDIN33) and VDDBU (or VBAT, respectively), based on the
+ * availability of these power sources.
+ *
+ * If the Backup Unit Power Switch is already in automatic mode, no action is
+ * required. If it is in software-controlled mode, it is switched to automatic
+ * mode to enhance safety and eliminate the need for toggling between power
+ * sources.
+ */
+static void at91_pm_switch_ba_to_auto(void)
 {
 	unsigned int offset = offsetof(struct at91_pm_sfrbu_regs, pswbu);
 	unsigned int val;
@@ -609,24 +623,19 @@ static void at91_pm_switch_ba_to_vbat(void)
 
 	val = readl(soc_pm.data.sfrbu + offset);
 
-	/* Already on VBAT. */
-	if (!(val & soc_pm.sfrbu_regs.pswbu.state))
+	/* Already on auto/hardware. */
+	if (!(val & soc_pm.sfrbu_regs.pswbu.ctrl))
 		return;
 
-	val &= ~soc_pm.sfrbu_regs.pswbu.softsw;
-	val |= soc_pm.sfrbu_regs.pswbu.key | soc_pm.sfrbu_regs.pswbu.ctrl;
+	val &= ~soc_pm.sfrbu_regs.pswbu.ctrl;
+	val |= soc_pm.sfrbu_regs.pswbu.key;
 	writel(val, soc_pm.data.sfrbu + offset);
-
-	/* Wait for update. */
-	val = readl(soc_pm.data.sfrbu + offset);
-	while (val & soc_pm.sfrbu_regs.pswbu.state)
-		val = readl(soc_pm.data.sfrbu + offset);
 }
 
 static void at91_pm_suspend(suspend_state_t state)
 {
 	if (soc_pm.data.mode == AT91_PM_BACKUP) {
-		at91_pm_switch_ba_to_vbat();
+		at91_pm_switch_ba_to_auto();
 
 		cpu_suspend(0, at91_suspend_finish);