netdev - RE: [PATCH v2 1/2] gpio: mlxbf2: Introduce IRQ support

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Date:   Wed, 22 Sep 2021 14:16:40 +0000
From:   Asmaa Mnebhi <asmaa@...dia.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "andy.shevchenko@...il.com" <andy.shevchenko@...il.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "bgolaszewski@...libre.com" <bgolaszewski@...libre.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>,
        David Thompson <davthompson@...dia.com>
Subject: RE: [PATCH v2 1/2] gpio: mlxbf2: Introduce IRQ support


> +static int
> +mlxbf2_gpio_irq_set_type(struct irq_data *irqd, unsigned int type) {
> +
> +	switch (type & IRQ_TYPE_SENSE_MASK) {
> +	case IRQ_TYPE_EDGE_BOTH:
> +		fall = true;
> +		rise = true;
> +		break;
> +	case IRQ_TYPE_EDGE_RISING:
> +		rise = true;
> +		break;
> +	case IRQ_TYPE_EDGE_FALLING:
> +		fall = true;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}

> What PHY are you using? I think every one i've looked at are 
> level triggered, not edge. Using an edge interrupt might work 99% 
> of the time, but when the timing is just wrong, you can loose an interrupt.
> Which might mean phylib thinks the link is down, when it fact it is up. 
> You will need to unplug and replug to recover from that.

It is the micrel PHY KSZ9031 so it is an active low level interrupt.
Here, IRQ_TYPE_EDGE* macros are mainly used to decide whether to write the
YU_GPIO_CAUSE_FALL_EN register vs the YU_GPIO_CAUSE_RISE_EN register.
These 2 registers are used in both LEVEL/EDGE interrupts.
So I will add back the IRQ_TYPE_LEVEL_LOW and IRQ_TYPE_LEVEL_HIGH as I
did before to configure YU_GPIO_CAUSE_FALL_EN and
YU_GPIO_CAUSE_HIGH_EN respectively. The PHY interrupt signal is physically
Connected to an open drain GPIO pin so software only needs to set
YU_GPIO_CAUSE_FALL_EN register in this case.

Thanks.
Asmaa