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From:   Asmaa Mnebhi <asmaa@nvidia.com>
To:     Andrew Lunn <andrew@lunn.ch>
CC:     Linus Walleij <linus.walleij@linaro.org>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        "David S. Miller" <davem@davemloft.net>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        David Thompson <davthompson@nvidia.com>
Subject: RE: [PATCH v3 1/2] gpio: mlxbf2: Introduce IRQ support
Thread-Topic: [PATCH v3 1/2] gpio: mlxbf2: Introduce IRQ support
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Date:   Fri, 8 Oct 2021 14:47:21 +0000
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> In KSZ9031, Register MII_KSZPHY_INTCS=3D0x1B reports all interrupt=20
> events and clear on read. So if there are 4 different interrupts, once it=
 is read once, all 4 clear at once.
> The micrel.c driver has defined ack_interrupt to read the above reg=20
> and is called every time the interrupt handler phy_interrupt is called. S=
o in this case, we should be good.
> The code flow in our case would look like this:
> - 2 interrupt sources (for example, link down followed by link up) set=20
> in MII_KSZPHY_INTCS
> - interrupt handler (phy_interrupt) reads MII_KSZPHY_INT which=20
> automatically clears both interrupts
> - another internal source triggers and sets the register.
> - The second edge will be caught accordingly by the GPIO.

> I still think there is a small race window. You product manager needs to =
decide if that is acceptable, or if you should poll the PHY.

I talked to both our managers and the HW team and they said it is ok to use=
 the interrupt for our product.

> Anyway, it is clear the hardware only does level interrupts, so the GPIO =
driver should only accept level interrupts. -EINVAL otherwise.

There is an on going conversation with HW folks to address this for future =
BlueField generations.

Thank you.
Asmaa