On Wed, Jun 09, 2021 at 04:12:36PM +0100, Jonathan Cameron wrote:

On Wed,  9 Jun 2021 10:31:07 +0900
William Breathitt Gray [off-list ref] wrote:

quoted

The 104-QUAD-8 only has two count modes where a ceiling value makes
sense: Range Limit and Modulo-N. Outside of these two modes, setting a
ceiling value is an invalid operation -- so let's report it as such by
returning -EINVAL.

Fixes: fc069262261c ("counter: 104-quad-8: Add lock guards - generic interface")
Acked-by: Syed Nayyar Waris <redacted>
Signed-off-by: William Breathitt Gray <redacted>

We seem to have some inconsistency in the driver about whether
we hold the priv->lock when calling quad8_preset_register_set()

Can we look to make that consistent?

We do need to hold the lock when calling quad8_preset_register_set()
lest priv->preset goes out of sync with the device state.

Syed, if you have no objections I'll adjust this in the next version.

William Breathitt Gray

quoted

---
 drivers/counter/104-quad-8.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index 4bb9abffae48..233a3acc1377 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c

@@ -714,13 +714,14 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter,
 	switch (priv->count_mode[count->id]) {
 	case 1:
 	case 3:
+		mutex_unlock(&priv->lock);

Probably swap this line and the next one...]

quoted

 		quad8_preset_register_set(priv, count->id, ceiling);
-		break;
+		return len;
 	}
 
 	mutex_unlock(&priv->lock);
 
-	return len;
+	return -EINVAL;
 }
 
 static ssize_t quad8_count_preset_enable_read(struct counter_device *counter,