linux-kernel - Re: [PATCH net-next v6 11/12] net: pse-pd: tps23881: Add support for static port priority feature

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Message-ID: <Z9gklcNz6wHU9cPC@pengutronix.de>
Date: Mon, 17 Mar 2025 14:33:09 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Kory Maincent <kory.maincent@...tlin.com>
Cc: Andrew Lunn <andrew@...n.ch>, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Donald Hunter <donald.hunter@...il.com>,
	Rob Herring <robh@...nel.org>, Andrew Lunn <andrew+netdev@...n.ch>,
	Simon Horman <horms@...nel.org>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	netdev@...r.kernel.org, linux-doc@...r.kernel.org,
	Kyle Swenson <kyle.swenson@....tech>,
	Dent Project <dentproject@...uxfoundation.org>,
	kernel@...gutronix.de,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v6 11/12] net: pse-pd: tps23881: Add support for
 static port priority feature

On Tue, Mar 04, 2025 at 11:19:00AM +0100, Kory Maincent wrote:
> From: Kory Maincent (Dent Project) <kory.maincent@...tlin.com>
> 
> This patch enhances PSE callbacks by introducing support for the static
> port priority feature. It extends interrupt management to handle and report
> detection, classification, and disconnection events. Additionally, it
> introduces the pi_get_pw_req() callback, which provides information about
> the power requested by the Powered Devices.
> 
> Interrupt support is essential for the proper functioning of the TPS23881
> controller. Without it, after a power-on (PWON), the controller will
> no longer perform detection and classification. This could lead to
> potential hazards, such as connecting a non-PoE device after a PoE device,
> which might result in magic smoke.
> 
> Signed-off-by: Kory Maincent (Dent Project) <kory.maincent@...tlin.com>
> ---
> 
> We may need a fix for the interrupt support in old version of Linux.
> 
> Change in v4:
> - Fix variable type nit.
> 
> Change in v3:
> - New patch
> ---
>  drivers/net/pse-pd/tps23881.c | 204 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 194 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
> index 1226667192977..6012c58b47e8a 100644
> --- a/drivers/net/pse-pd/tps23881.c
> +++ b/drivers/net/pse-pd/tps23881.c
> @@ -19,20 +19,30 @@
>  
>  #define TPS23881_REG_IT		0x0
>  #define TPS23881_REG_IT_MASK	0x1
> +#define TPS23881_REG_IT_DISF	BIT(2)
> +#define TPS23881_REG_IT_DETC	BIT(3)
> +#define TPS23881_REG_IT_CLASC	BIT(4)
>  #define TPS23881_REG_IT_IFAULT	BIT(5)
>  #define TPS23881_REG_IT_SUPF	BIT(7)
> +#define TPS23881_REG_DET_EVENT	0x5
>  #define TPS23881_REG_FAULT	0x7
>  #define TPS23881_REG_SUPF_EVENT	0xb
>  #define TPS23881_REG_TSD	BIT(7)
> +#define TPS23881_REG_DISC	0xc
>  #define TPS23881_REG_PW_STATUS	0x10
>  #define TPS23881_REG_OP_MODE	0x12
> +#define TPS23881_REG_DISC_EN	0x13
>  #define TPS23881_OP_MODE_SEMIAUTO	0xaaaa
>  #define TPS23881_REG_DIS_EN	0x13
>  #define TPS23881_REG_DET_CLA_EN	0x14
>  #define TPS23881_REG_GEN_MASK	0x17
> +#define TPS23881_REG_CLCHE	BIT(2)
> +#define TPS23881_REG_DECHE	BIT(3)
>  #define TPS23881_REG_NBITACC	BIT(5)
>  #define TPS23881_REG_INTEN	BIT(7)
>  #define TPS23881_REG_PW_EN	0x19
> +#define TPS23881_REG_RESET	0x1a
> +#define TPS23881_REG_CLRAIN	BIT(7)
>  #define TPS23881_REG_2PAIR_POL1	0x1e
>  #define TPS23881_REG_PORT_MAP	0x26
>  #define TPS23881_REG_PORT_POWER	0x29
> @@ -177,6 +187,7 @@ static int tps23881_pi_enable(struct pse_controller_dev *pcdev, int id)
>  	struct i2c_client *client = priv->client;
>  	u8 chan;
>  	u16 val;
> +	int ret;
>  
>  	if (id >= TPS23881_MAX_CHANS)
>  		return -ERANGE;
> @@ -190,7 +201,22 @@ static int tps23881_pi_enable(struct pse_controller_dev *pcdev, int id)
>  				       BIT(chan % 4));
>  	}
>  
> -	return i2c_smbus_write_word_data(client, TPS23881_REG_PW_EN, val);
> +	ret = i2c_smbus_write_word_data(client, TPS23881_REG_PW_EN, val);
> +	if (ret)
> +		return ret;
> +
> +	/* Enable DC disconnect*/
> +	chan = priv->port[id].chan[0];
> +	ret = i2c_smbus_read_word_data(client, TPS23881_REG_DISC_EN);
> +	if (ret < 0)
> +		return ret;

Here we have RMW operation without lock on two paths: pi_enable and
pi_disable.

> +	val = tps23881_set_val(ret, chan, 0, BIT(chan % 4), BIT(chan % 4));
> +	ret = i2c_smbus_write_word_data(client, TPS23881_REG_DISC_EN, val);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
>  }
>  
>  static int tps23881_pi_disable(struct pse_controller_dev *pcdev, int id)
> @@ -223,6 +249,17 @@ static int tps23881_pi_disable(struct pse_controller_dev *pcdev, int id)
>  	 */
>  	mdelay(5);
>  
> +	/* Disable DC disconnect*/
> +	chan = priv->port[id].chan[0];
> +	ret = i2c_smbus_read_word_data(client, TPS23881_REG_DISC_EN);
> +	if (ret < 0)
> +		return ret;

dito

> +	val = tps23881_set_val(ret, chan, 0, 0, BIT(chan % 4));
> +	ret = i2c_smbus_write_word_data(client, TPS23881_REG_DISC_EN, val);
> +	if (ret)
> +		return ret;
> +
-- 
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