netdev - Re: [PATCH net-next v7 6/9] net: txgbe: Support GPIO to SFP socket

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Message-ID: <f9e0da51-6c55-4768-aa27-437bb7f19888@lunn.ch>
Date: Thu, 11 May 2023 14:38:51 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Jiawen Wu <jiawenwu@...stnetic.com>
Cc: netdev@...r.kernel.org, jarkko.nikula@...ux.intel.com,
	andriy.shevchenko@...ux.intel.com, mika.westerberg@...ux.intel.com,
	jsd@...ihalf.com, Jose.Abreu@...opsys.com, hkallweit1@...il.com,
	linux@...linux.org.uk, linux-i2c@...r.kernel.org,
	linux-gpio@...r.kernel.org, mengyuanlou@...-swift.com
Subject: Re: [PATCH net-next v7 6/9] net: txgbe: Support GPIO to SFP socket

> +static int txgbe_gpio_set_type(struct irq_data *d, unsigned int type)
> +{
> +	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
> +	irq_hw_number_t hwirq = irqd_to_hwirq(d);
> +	struct wx *wx = gpiochip_get_data(gc);
> +	u32 level, polarity;
> +
> +	level = rd32(wx, WX_GPIO_INTTYPE_LEVEL);
> +	polarity = rd32(wx, WX_GPIO_POLARITY);
> +
> +	switch (type) {
> +	case IRQ_TYPE_EDGE_BOTH:
> +		level |= BIT(hwirq);
> +		break;
> +	case IRQ_TYPE_EDGE_RISING:
> +		level |= BIT(hwirq);
> +		polarity |= BIT(hwirq);
> +		break;
> +	case IRQ_TYPE_EDGE_FALLING:
> +		level |= BIT(hwirq);
> +		polarity &= ~BIT(hwirq);
> +		break;
> +	case IRQ_TYPE_LEVEL_HIGH:
> +		level &= ~BIT(hwirq);
> +		polarity |= BIT(hwirq);
> +		break;
> +	case IRQ_TYPE_LEVEL_LOW:
> +		level &= ~BIT(hwirq);
> +		polarity &= ~BIT(hwirq);
> +		break;
> +	}

You have two configuration bits, level and polarity, yet handle 5
different types?

> +	wr32m(wx, WX_GPIO_INTEN, BIT(hwirq), BIT(hwirq));
> +	wr32(wx, WX_GPIO_INTTYPE_LEVEL, level);
> +	if (type != IRQ_TYPE_EDGE_BOTH)
> +		wr32(wx, WX_GPIO_POLARITY, polarity);

If we are interested in both edges, then polarity is meaningless. So i
can understand not writing it. But how does the hardware know polarity
should not be used?

       Andrew