Subject: Re: [PATCH net-next] net: phy: micrel: Add support for PTP_PF_PEROUT for lan8841

From: "Russell King (Oracle)" <[email-masked]>
Date: Fri, 17 Feb 2023 13:30:06 +0000

On Fri, Feb 17, 2023 at 08:52:13AM +0100, Horatiu Vultur wrote:
> +static void lan8841_ptp_perout_off(struct kszphy_ptp_priv *ptp_priv, int pin)
> +{
> +	struct phy_device *phydev = ptp_priv->phydev;
> +	u16 tmp;
> +
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_EN) & LAN8841_PTP_GPIO_MASK;
> +	tmp &= ~BIT(pin);
> +	phy_write_mmd(phydev, 2, LAN8841_GPIO_EN, tmp);

Problem 1: doesn't check the return value of phy_read_mmd(), so a
spurious error results in an error code written back to the register.

Issue 2: please use phy_modify_mmd() and definitions for the MMD. It
probably also makes sense to cache the mask. Thus, this whole thing
becomes:

	u16 mask = ~(LAN8841_PTP_GPIO_MASK | BIT(pin));

	phy_modify_mmd(phydev, MDIO_MMD_WIS, LAN8841_GPIO_EN, mask, 0);
	phy_modify_mmd(phydev, MDIO_MMD_WIS, LAN8841_GPIO_DIR, mask, 0);
	phy_modify_mmd(phydev, MDIO_MMD_WIS, LAN8841_GPIO_BUF, mask, 0);

although I'm not sure why you need to mask off bits 15:11.

> +
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_DIR) & LAN8841_PTP_GPIO_MASK;
> +	tmp &= ~BIT(pin);
> +	phy_write_mmd(phydev, 2, LAN8841_GPIO_DIR, tmp);
> +
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_BUF) & LAN8841_PTP_GPIO_MASK;
> +	tmp &= ~BIT(pin);
> +	phy_write_mmd(phydev, 2, LAN8841_GPIO_BUF, tmp);
> +}
> +
> +static void lan8841_ptp_perout_on(struct kszphy_ptp_priv *ptp_priv, int pin)
> +{
> +	struct phy_device *phydev = ptp_priv->phydev;
> +	u16 tmp;
> +
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_EN) & LAN8841_PTP_GPIO_MASK;
> +	tmp |= BIT(pin);
> +	phy_write_mmd(phydev, 2, LAN8841_GPIO_EN, tmp);
> +
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_DIR) & LAN8841_PTP_GPIO_MASK;
> +	tmp |= BIT(pin);
> +	phy_write_mmd(phydev, 2, LAN8841_GPIO_DIR, tmp);
> +
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_BUF) & LAN8841_PTP_GPIO_MASK;
> +	tmp |= BIT(pin);
> +	phy_write_mmd(phydev, 2, LAN8841_GPIO_BUF, tmp);

Similar as above.

> +static void lan8841_ptp_remove_event(struct kszphy_ptp_priv *ptp_priv, int pin,
> +				     u8 event)
> +{
> +	struct phy_device *phydev = ptp_priv->phydev;
> +	u8 offset;
> +	u16 tmp;
> +
> +	/* Not remove pin from the event. GPIO_DATA_SEL1 contains the GPIO
> +	 * pins 0-4 while GPIO_DATA_SEL2 contains GPIO pins 5-9, therefore
> +	 * depending on the pin, it requires to read a different register
> +	 */
> +	if (pin < 5) {
> +		tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_DATA_SEL1);
> +		offset = pin;
> +	} else {
> +		tmp = phy_read_mmd(phydev, 2, LAN8841_GPIO_DATA_SEL2);
> +		offset = pin - 5;
> +	}
> +	tmp &= ~(LAN8841_GPIO_DATA_SEL_GPIO_DATA_SEL_EVENT_MASK << (3 * offset));
> +	if (pin < 5)
> +		phy_write_mmd(phydev, 2, LAN8841_GPIO_DATA_SEL1, tmp);
> +	else
> +		phy_write_mmd(phydev, 2, LAN8841_GPIO_DATA_SEL2, tmp);

This could be much simpler using phy_modify_mmd().

> +
> +	/* Disable the event */
> +	tmp = phy_read_mmd(phydev, 2, LAN8841_PTP_GENERAL_CONFIG);
> +	if (event == LAN8841_EVENT_A) {
> +		tmp &= ~LAN8841_PTP_GENERAL_CONFIG_LTC_EVENT_POL_A;
> +		tmp &= ~LAN8841_PTP_GENERAL_CONFIG_LTC_EVENT_A_MASK;
> +	} else {
> +		tmp &= ~LAN8841_PTP_GENERAL_CONFIG_LTC_EVENT_POL_A;
> +		tmp &= ~LAN8841_PTP_GENERAL_CONFIG_LTC_EVENT_A_MASK;
> +	}
> +	phy_write_mmd(phydev, 2, LAN8841_PTP_GENERAL_CONFIG, tmp);

Ditto... and the theme seems to continue throughout the rest of this
patch.

> +static int lan8841_ptp_perout(struct ptp_clock_info *ptp,
> +			      struct ptp_clock_request *rq, int on)
> +{
> +	struct kszphy_ptp_priv *ptp_priv = container_of(ptp, struct kszphy_ptp_priv,
> +							ptp_clock_info);
> +	struct phy_device *phydev = ptp_priv->phydev;
> +	struct timespec64 ts_on, ts_period;
> +	s64 on_nsec, period_nsec;
> +	int pulse_width;
> +	int pin;
> +
> +	if (rq->perout.flags & ~PTP_PEROUT_DUTY_CYCLE)
> +		return -EOPNOTSUPP;
> +
> +	pin = ptp_find_pin(ptp_priv->ptp_clock, PTP_PF_PEROUT, rq->perout.index);
> +	if (pin == -1 || pin >= LAN8841_PTP_GPIO_NUM)
> +		return -EINVAL;
> +
> +	if (!on) {
> +		lan8841_ptp_perout_off(ptp_priv, pin);
> +		lan8841_ptp_remove_event(ptp_priv, LAN8841_EVENT_A, pin);
> +		return 0;
> +	}
> +
> +	ts_on.tv_sec = rq->perout.on.sec;
> +	ts_on.tv_nsec = rq->perout.on.nsec;
> +	on_nsec = timespec64_to_ns(&ts_on);
> +
> +	ts_period.tv_sec = rq->perout.period.sec;
> +	ts_period.tv_nsec = rq->perout.period.nsec;
> +	period_nsec = timespec64_to_ns(&ts_period);
> +
> +	if (period_nsec < 200) {
> +		phydev_warn(phydev,
> +			    "perout period too small, minimum is 200 nsec\n");

I'm not sure using the kernel log to print such things is a good idea,
especially without rate limiting.

> @@ -3874,7 +4220,24 @@ static int lan8841_probe(struct phy_device *phydev)
>  	priv = phydev->priv;
>  	ptp_priv = &priv->ptp_priv;
>  
> +	ptp_priv->pin_config = devm_kmalloc_array(&phydev->mdio.dev,
> +						  LAN8841_PTP_GPIO_NUM,
> +						  sizeof(*ptp_priv->pin_config),
> +						  GFP_KERNEL);

devm_kcalloc() to avoid the memset() below?

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