[PATCH v3] mfd: stpmic1: Attempt system shutdown twice in case PMIC is confused

[Marek Vasut <marex@nabladev.com>]

Attempt to shut down again, in case the first attempt failed.
The STPMIC1 might get confused and the first regmap_update_bits()
returns with -ETIMEDOUT / -110 . If that or similar transient
failure occurs, try to shut down again. If the second attempt
fails, there is some bigger problem, report it to user.

Cc: stable@vger.kernel.org
Fixes: 6e9df38f359a ("mfd: stpmic1: Add PMIC poweroff via sys-off handler")
Signed-off-by: Marek Vasut <marex@nabladev.com>
---
Cc: Lee Jones <lee@kernel.org>
Cc: Pascal PAILLET-LME <p.paillet@st.com>
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Sean Nyekjaer <sean@geanix.com>
Cc: kernel@dh-electronics.com
---
V2: - Use a retry loop
    - Cc stable
V3: Adjust the loop further, define STPMIC1_MAX_RETRIES, rename
    the loop control variable, print error message only when the
    loop ran STPMIC1_MAX_RETRIES times
---
 drivers/mfd/stpmic1.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/stpmic1.c b/drivers/mfd/stpmic1.c
index 081827bc05961..7c677b0344c60 100644
--- a/drivers/mfd/stpmic1.c
+++ b/drivers/mfd/stpmic1.c
@@ -16,6 +16,8 @@
 
 #include <dt-bindings/mfd/st,stpmic1.h>
 
+#define STPMIC1_MAX_RETRIES 2
+
 #define STPMIC1_MAIN_IRQ 0
 
 static const struct regmap_range stpmic1_readable_ranges[] = {
@@ -121,9 +123,23 @@ static const struct regmap_irq_chip stpmic1_regmap_irq_chip = {
 static int stpmic1_power_off(struct sys_off_data *data)
 {
 	struct stpmic1 *ddata = data->cb_data;
+	int ret;
+
+	/*
+	 * Attempt to shut down again, in case the first attempt failed.
+	 * The STPMIC1 might get confused and the first regmap_update_bits()
+	 * returns with -ETIMEDOUT / -110 . If that or similar transient
+	 * failure occurs, try to shut down again. If the second attempt
+	 * fails, there is some bigger problem, report it to user.
+	 */
+	for (int retries = 0; retries < STPMIC1_MAX_RETRIES; retries++) {
+		ret = regmap_update_bits(ddata->regmap, MAIN_CR, SOFTWARE_SWITCH_OFF,
+					 SOFTWARE_SWITCH_OFF);
+		if (!ret)
+			return NOTIFY_DONE;
+	}
 
-	regmap_update_bits(ddata->regmap, MAIN_CR,
-			   SOFTWARE_SWITCH_OFF, SOFTWARE_SWITCH_OFF);
+	dev_err(ddata->dev, "Failed to access PMIC I2C bus (%d)\n", ret);
 
 	return NOTIFY_DONE;
 }
-- 
2.51.0