[PATCH 4/5] regulator: mt6363: Fix interrmittent timeout

[Adam Ford <aford173@gmail.com>]

Sometimes, the mt6363 regulator would fail to initialize and return with
a TIMEOUT error, so add an extra instruction to wake up the bus before
issuing the commands.

Fixes: 3c36965df808 ("regulator: Add support for MediaTek MT6363 SPMI PMIC Regulators")
Signed-off-by: Adam Ford <aford173@gmail.com>
---
 drivers/regulator/mt6363-regulator.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/regulator/mt6363-regulator.c b/drivers/regulator/mt6363-regulator.c
index e0fbf92e7685..03af5fa53600 100644
--- a/drivers/regulator/mt6363-regulator.c
+++ b/drivers/regulator/mt6363-regulator.c
@@ -861,7 +861,7 @@ static int mt6363_regulator_probe(struct platform_device *pdev)
 	struct irq_domain *domain;
 	struct irq_fwspec fwspec;
 	struct spmi_device *sdev;
-	int i, ret;
+	int i, ret, val;
 
 	config.regmap = mt6363_spmi_register_regmap(dev);
 	if (IS_ERR(config.regmap))
@@ -870,6 +870,13 @@ static int mt6363_regulator_probe(struct platform_device *pdev)
 	config.dev = dev;
 	sdev = to_spmi_device(dev->parent);
 
+	/*
+	 * The first read may fail if the bootloader sets sleep mode: wake up
+	 * this PMIC with W/R on the SPMI bus and ignore the first result.
+	 * This matches the MT6373 driver behavior.
+	 */
+	regmap_read(config.regmap, MT6363_TOP_TRAP, &val);
+
 	interrupt_parent = of_irq_find_parent(dev->of_node);
 	if (!interrupt_parent)
 		return dev_err_probe(dev, -EINVAL, "Cannot find IRQ parent\n");
-- 
2.51.0