Merge branch 'net-pse-pd-si3474-two-driver-fixes'

Piotr Kubik says:

====================
net: pse-pd: si3474: two driver fixes

Two fixes for the Si3474 PSE driver, found while preparing 2-pair and
semi-auto support for it.

Patch 1 stops si3474_pi_enable() from clearing detection and
classification of the other PI in the same quad. Without it, a PD on
that PI gets no power after a later plug-in.

Patch 2 rejects a channel number of 8 and a 4-pair PI whose channels
are not one channel pair of a quad.

Both were tested on an SDG-9000 board (MediaTek MT7988A, two Si3474)
with a Linux 6.18 kernel that carries the same patches, and build-tested
on the net tree.
====================

Link: https://patch.msgid.link/20261019162453.1244120-1-piotr@kubik.pl
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 19 insertions, 4 deletions

diff --git a/drivers/net/pse-pd/si3474.c b/drivers/net/pse-pd/si3474.c
index efb0af041599..35152d462e82 100644
--- a/drivers/net/pse-pd/si3474.c
+++ b/drivers/net/pse-pd/si3474.c
@@ -250,9 +250,9 @@ static int si3474_get_of_channels(struct si3474_priv *priv)
 					"Failed to read channel reg property\n");
 				return ret;
 			}
-			if (chan_id > SI3474_MAX_CHANS) {
+			if (chan_id >= SI3474_MAX_CHANS) {
 				dev_err(&priv->client[0]->dev,
-					"Incorrect channel number: %d\n", chan_id);
+					"Incorrect channel number: %u\n", chan_id);
 				return -EINVAL;
 			}
 
@@ -267,6 +267,16 @@ static int si3474_get_of_channels(struct si3474_priv *priv)
 				pi->np);
 			return -EINVAL;
 		}
+
+		/* The 2P/4P mode bit pairs channels 0+1 and 2+3 of a quad */
+		if (pairset_found &&
+		    (priv->pi[pi_no].chan[0] ^ 1) != priv->pi[pi_no].chan[1]) {
+			dev_err(&priv->client[0]->dev,
+				"PI %pOF: channels %u and %u are not a channel pair\n",
+				pi->np, priv->pi[pi_no].chan[0],
+				priv->pi[pi_no].chan[1]);
+			return -EINVAL;
+		}
 	}
 
 	return 0;
@@ -312,8 +322,13 @@ static int si3474_pi_enable(struct pse_controller_dev *pcdev, int id)
 	/* DETECT_CLASS_ENABLE must be set when using AUTO mode,
 	 * otherwise PI does not power up - datasheet section 2.10.2
 	 */
-	val = CHAN_BIT(chan0) | CHAN_UPPER_BIT(chan0) |
-	      CHAN_BIT(chan1) | CHAN_UPPER_BIT(chan1);
+	ret = i2c_smbus_read_byte_data(client, DETECT_CLASS_ENABLE_REG);
+	if (ret < 0)
+		return ret;
+
+	val = (u8)ret;
+	val |= CHAN_BIT(chan0) | CHAN_UPPER_BIT(chan0) |
+	       CHAN_BIT(chan1) | CHAN_UPPER_BIT(chan1);
 
 	ret = i2c_smbus_write_byte_data(client, DETECT_CLASS_ENABLE_REG, val);
 	if (ret)