[PATCH v2 06/13] regulator: ab8500: Propagate mode enable read errors

[Linus Walleij <linusw@kernel.org>]

For regulators whose enable and mode share a state field, set_mode()
first reads that field so changing the requested mode does not enable a
disabled rail. A register read error is currently treated as true and
the driver proceeds to write the new mode, potentially enabling a rail
whose state is unknown.

Return the read error without changing the register or cached mode.

References: AB8500 User Manual, UM0836 Rev 3, p. 227;
AB8505 User Manual, DM00046744 Rev 3, p. 237

Fixes: 438e695b87e0 ("regulator: ab8500: Get rid of is_enabled from struct ab8500_regulator_info")
Assisted-by: LLM
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
 drivers/regulator/ab8500.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/ab8500.c b/drivers/regulator/ab8500.c
index 05c6b9c7af0c..e4c3502c8dbc 100644
--- a/drivers/regulator/ab8500.c
+++ b/drivers/regulator/ab8500.c
@@ -433,7 +433,7 @@ static unsigned int ab8500_regulator_get_optimum_mode(
 static int ab8500_regulator_set_mode(struct regulator_dev *rdev,
 				     unsigned int mode)
 {
-	int ret = 0;
+	int enabled, ret = 0;
 	u8 bank, reg, mask, val;
 	bool lp_mode_req = false;
 	struct ab8500_regulator_info *info = rdev_get_drvdata(rdev);
@@ -490,7 +490,17 @@ static int ab8500_regulator_set_mode(struct regulator_dev *rdev,
 		goto out_unlock;
 	}
 
-	if (info->mode_mask || ab8500_regulator_is_enabled(rdev)) {
+	if (info->mode_mask) {
+		enabled = 1;
+	} else {
+		enabled = ab8500_regulator_is_enabled(rdev);
+		if (enabled < 0) {
+			ret = enabled;
+			goto out_unlock;
+		}
+	}
+
+	if (enabled) {
 		ret = abx500_mask_and_set_register_interruptible(info->dev,
 			bank, reg, mask, val);
 		if (ret < 0) {

-- 
2.55.0