linux-kernel - Re: [EXTERNAL]Re: [PATCH net-next v4 2/2] net: pse-pd: Add Si3474 PSE controller driver

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Message-ID: <53c71efc-e29b-482a-bd6a-7a66a2d2d415@adtran.com>
Date: Thu, 10 Jul 2025 15:32:11 +0000
From: Piotr Kubik <piotr.kubik@...ran.com>
To: Kory Maincent <kory.maincent@...tlin.com>
CC: Oleksij Rempel <o.rempel@...gutronix.de>, Andrew Lunn
	<andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
	<krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [EXTERNAL]Re: [PATCH net-next v4 2/2] net: pse-pd: Add Si3474 PSE
 controller driver

On 7/7/25 15:17, Kory Maincent wrote:
> ...
> 
> 
>> +
>> +static int si3474_pi_enable(struct pse_controller_dev *pcdev, int id)
>> +{
>> +	struct si3474_priv *priv = to_si3474_priv(pcdev);
>> +	struct i2c_client *client;
>> +	u8 chan0, chan1;
>> +	u8 val = 0;
>> +	s32 ret;
>> +
>> +	if (id >= SI3474_MAX_CHANS)
>> +		return -ERANGE;
>> +
>> +	si3474_get_channels(priv, id, &chan0, &chan1);
>> +	client = si3474_get_chan_client(priv, chan0);
>> +
>> +	/* Release PI from shutdown */
>> +	ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	val = (u8)ret;
>> +	val |= CHAN_MASK(chan0);
>> +	val |= CHAN_MASK(chan1);
>> +
>> +	ret = i2c_smbus_write_byte_data(client, PORT_MODE_REG, val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* DETECT_CLASS_ENABLE must be set when using AUTO mode,
>> +	 * otherwise PI does not power up - datasheet section 2.10.2
>> +	 */
> 
> What happen in a PD disconnection case? According to the datasheet it simply
> raise a disconnection interrupt and disconnect the power with a
> DISCONNECT_PCUT_FAULT fault. But it is not clear if it goes back to the
> detection + classification process. If it is not the case you will face the
> same issue I did and will need to deal with the interrupt and the disconnection
> management.
> 
> Could you try to enable a port, plug a PD then disconnect it and plug another PD
> which belong to another power class. Finally read the class detected to verify that the
> class detected have changed.

Yes, I did this test, also with disabling/enabling PI in between PD disconnects/connects. 
Each time class was detected correctly (class4 vs 3 in my case). 
I checked also class results when no PD was connected or PI was disabled, all OK.


Thanks, 
/Piotr