linux-kernel - Re: [PATCH net-next v4 4/4] net: phy: dp83td510: Add support for the DP83TD510 Ethernet PHY

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Date:   Tue, 17 Nov 2020 22:57:00 +0200
From:   Ioana Ciornei <ciorneiioana@...il.com>
To:     Dan Murphy <dmurphy@...com>
Cc:     davem@...emloft.net, andrew@...n.ch, f.fainelli@...il.com,
        hkallweit1@...il.com, robh@...nel.org, ciorneiioana@...il.com,
        devicetree@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v4 4/4] net: phy: dp83td510: Add support for the
 DP83TD510 Ethernet PHY

On Tue, Nov 17, 2020 at 02:15:55PM -0600, Dan Murphy wrote:
> The DP83TD510E is an ultra-low power Ethernet physical layer transceiver
> that supports 10M single pair cable.
> 
> The device supports both 2.4-V p2p and 1-V p2p output voltage as defined
> by IEEE 802.3cg 10Base-T1L specfications. These modes can be forced via
> the device tree or the device is defaulted to auto negotiation to
> determine the proper p2p voltage.
> 
> Signed-off-by: Dan Murphy <dmurphy@...com>
> ---
> 
> v4 - Considerable rework of the code after secondary test setup was created.
> This version also uses the handle_interrupt call back and reduces the
> configuration arrays as it was determined that 80% of the array was the same.
> 
>  drivers/net/phy/Kconfig     |   6 +
>  drivers/net/phy/Makefile    |   1 +
>  drivers/net/phy/dp83td510.c | 505 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 512 insertions(+)
>  create mode 100644 drivers/net/phy/dp83td510.c
> 

[snip]

> +static int dp83td510_ack_interrupt(struct phy_device *phydev)
> +{
> +	int ret;
> +
> +	ret = phy_read(phydev, DP83TD510_INT_REG1);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = phy_read(phydev, DP83TD510_INT_REG2);
> +	if (ret < 0)
> +		return ret;
> +
> +	phy_trigger_machine(phydev);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t dp83td510_handle_interrupt(struct phy_device *phydev)
> +{
> +	int ret;
> +
> +	ret = dp83td510_ack_interrupt(phydev);
> +	if (ret)
> +		return IRQ_NONE;
> +
> +	return IRQ_HANDLED;
> +}

>From what I can see in the datasheet, the INT_REG1 and INT_REG2 are used
for both interrupt configuration and interrupt status.

If this is the case, the state machine should only be triggered if the
interrupt was triggered (eg DP83TD510_INT1_LINK is set), not if _any_
bit from the register is set. This is broken since anytime you have
interrupts enabled, the lower half of the register will be non-zero
since that contains you interrupt enabled bits.

The .handle_interrupt() should look something like:

	ret = phy_read(phydev, DP83TD510_INT_REG1);
	if (ret < 0)
		return ret;
	
	if (!(ret & (DP83TD510_INT1_ESD | DP83TD510_INT1_LINK | DP83TD510_INT1_RHF)))
		return IRQ_NONE;

	ret = phy_read(phydev, DP83TD510_INT_REG2);
	if (ret < 0)
		return ret;
	
	if (!(ret & (DP83TD510_INT2_POR | DP83TD510_INT2_POL | DP83TD510_INT2_PAGE)))
		return IRQ_NONE;

	phy_trigger_machine(phydev);

	return IRQ_HANDLED;

> +
> +static int dp83td510_config_intr(struct phy_device *phydev)
> +{
> +	int int_status;
> +	int gen_cfg_val;
> +	int ret;
> +
> +	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
> +		int_status = phy_read(phydev, DP83TD510_INT_REG1);
> +		if (int_status < 0)
> +			return int_status;
> +
> +		int_status = (DP83TD510_INT1_ESD_EN | DP83TD510_INT1_LINK_EN |
> +			      DP83TD510_INT1_RHF_EN);
> +
> +		ret = phy_write(phydev, DP83TD510_INT_REG1, int_status);
> +		if (ret)
> +			return ret;
> +
> +		int_status = phy_read(phydev, DP83TD510_INT_REG2);
> +		if (int_status < 0)
> +			return int_status;
> +
> +		int_status = (DP83TD510_INT2_POR | DP83TD510_INT2_POL |
> +				DP83TD510_INT2_PAGE);
> +

Shouldn't you use DP83TD510_INT2_POR_EN, DP83TD510_INT2_POL_EN etc here?
It seems that you are setting up the bits corresponding with the
interrupt status and not the interrupt enable.

Ioana