[PATCH 0/2] mfd: gateworks-gsc: Propagate I2C write and store errors

[PATCH 0/2] mfd: gateworks-gsc: Propagate I2C write and store errors

[shao.mingyin]

The GSC regmap bus wraps register accesses in an I2C retry loop to work
around a chip errata, but gsc_write() throws away the result of the last
transfer.  Every write through regmap therefore looks successful, and
gsc_powerdown()'s existing error checks can never fire.  The powerdown
sysfs attribute has the same problem on a smaller scale: it ignores both
the argument parse error and the value returned by gsc_powerdown().

1/2 returns the last transfer result from gsc_write(), so regmap_write()
and gsc_powerdown()'s checks start to work.  2/2 returns the kstrtol()
and gsc_powerdown() errors from gsc_store() instead of reporting a
successful store; its gsc_powerdown() error path is only reachable with
1/2 applied.

The patches apply independently and can be applied in either order,
although 2/2's gsc_powerdown() error path only becomes reachable once
1/2 is in place.  The read counterpart in gsc_read() is handled by a
separate patch and is not a dependency here.

Shao Mingyin (2):
  mfd: gateworks-gsc: Propagate I2C write errors
  mfd: gateworks-gsc: Propagate errors from gsc_store()

 drivers/mfd/gateworks-gsc.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

---
base-commit: 7649ba73f9e7e1e04d0b46213e39c79ae09dd55c

[PATCH 1/2] mfd: gateworks-gsc: Propagate I2C write errors

[shao.mingyin]

From: Shao Mingyin <shao.mingyin@zte.com.cn>

gsc_write() retries the I2C transfer but then returns 0 unconditionally,
so regmap_write() and regmap_bulk_write() never report an error even when
all attempts failed.  Callers such as gsc_powerdown() check the return
value, but those checks can never trigger.

Return the result of the last transfer.

Fixes: d85234994b2f ("mfd: Add Gateworks System Controller core driver")
Signed-off-by: Shao Mingyin <shao.mingyin@zte.com.cn>
---
diff --git a/drivers/mfd/gateworks-gsc.c b/drivers/mfd/gateworks-gsc.c
index a3301502ce6a..aa2252402095 100644
--- a/drivers/mfd/gateworks-gsc.c
+++ b/drivers/mfd/gateworks-gsc.c
@@ -44,7 +44,7 @@ int gsc_write(void *context, unsigned int reg, unsigned int val)
 			break;
 	}
 
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(gsc_write);
 
-- 
2.47.0

[PATCH 2/2] mfd: gateworks-gsc: Propagate errors from gsc_store()

[shao.mingyin]

From: Shao Mingyin <shao.mingyin@zte.com.cn>

gsc_store() ignores both the kstrtol() result and the value returned by
gsc_powerdown(), so an invalid argument or a failed I2C write is reported
to userspace as a successful sysfs store.

Return both errors to the caller.  The gsc_powerdown() error only became
reachable with the preceding patch, which makes gsc_write() report I2C
failures.

Fixes: d85234994b2f ("mfd: Add Gateworks System Controller core driver")
Signed-off-by: Shao Mingyin <shao.mingyin@zte.com.cn>
---
diff --git a/drivers/mfd/gateworks-gsc.c b/drivers/mfd/gateworks-gsc.c
index aa2252402095..999cf84405ba 100644
--- a/drivers/mfd/gateworks-gsc.c
+++ b/drivers/mfd/gateworks-gsc.c
@@ -125,10 +125,16 @@ static ssize_t gsc_store(struct device *dev, struct device_attribute *attr,
 	struct gsc_dev *gsc = dev_get_drvdata(dev);
 	const char *name = attr->attr.name;
 	long value;
+	int ret;
 
 	if (strcasecmp(name, "powerdown") == 0) {
-		if (kstrtol(buf, 0, &value) == 0)
-			gsc_powerdown(gsc, value);
+		ret = kstrtol(buf, 0, &value);
+		if (ret)
+			return ret;
+
+		ret = gsc_powerdown(gsc, value);
+		if (ret)
+			return ret;
 	} else {
 		dev_err(dev, "invalid command: '%s\n", name);
 	}
-- 
2.47.0