linux-kernel - Re: [PATCH net-next 00/19] net: phy: add support for shared interrupts (part 1)

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Message-ID: <20201031105721.cc5g3he66ku6rm5b@skbuf>
Date:   Sat, 31 Oct 2020 12:57:21 +0200
From:   Ioana Ciornei <ciorneiioana@...il.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Ioana Ciornei <ciorneiioana@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Ioana Ciornei <ioana.ciornei@....com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Andre Edich <andre.edich@...rochip.com>,
        Antoine Tenart <atenart@...nel.org>,
        Baruch Siach <baruch@...s.co.il>,
        Christophe Leroy <christophe.leroy@....fr>,
        Dan Murphy <dmurphy@...com>,
        Divya Koppera <Divya.Koppera@...rochip.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Jerome Brunet <jbrunet@...libre.com>,
        Kavya Sree Kotagiri <kavyasree.kotagiri@...rochip.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Marco Felsch <m.felsch@...gutronix.de>,
        Marek Vasut <marex@...x.de>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Mathias Kresin <dev@...sin.me>,
        Maxim Kochetkov <fido_max@...ox.ru>,
        Michael Walle <michael@...le.cc>,
        Neil Armstrong <narmstrong@...libre.com>,
        Nisar Sayed <Nisar.Sayed@...rochip.com>,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        Willy Liu <willy.liu@...ltek.com>,
        Yuiko Oshino <yuiko.oshino@...rochip.com>
Subject: Re: [PATCH net-next 00/19] net: phy: add support for shared
 interrupts (part 1)

On Sat, Oct 31, 2020 at 11:18:18AM +0100, Heiner Kallweit wrote:
> On 31.10.2020 00:36, Andrew Lunn wrote:
> >>> - Every PHY driver gains a .handle_interrupt() implementation that, for
> >>>   the most part, would look like below:
> >>>
> >>> 	irq_status = phy_read(phydev, INTR_STATUS);
> >>> 	if (irq_status < 0) {
> >>> 		phy_error(phydev);
> >>> 		return IRQ_NONE;
> >>> 	}
> >>>
> >>> 	if (irq_status == 0)
> >>
> >> Here I have a concern, bits may be set even if the respective interrupt
> >> source isn't enabled. Therefore we may falsely blame a device to have
> >> triggered the interrupt. irq_status should be masked with the actually
> >> enabled irq source bits.
> > 
> > Hi Heiner
> > 
> Hi Andrew,
> 
> > I would say that is a driver implementation detail, for each driver to
> > handle how it needs to handle it. I've seen some hardware where the
> > interrupt status is already masked with the interrupt enabled
> > bits. I've soon other hardware where it is not.
> > 
> Sure, I just wanted to add the comment before others simply copy and
> paste this (pseudo) code. And in patch 9 (aquantia) and 18 (realtek)
> it is used as is. And IIRC at least the Aquantia PHY doesn't mask
> the interrupt status.
> 

Hi Heiner,

If I understand correctly what you are suggesting, the
.handle_interrupt() for the aquantia would look like this:

static irqreturn_t aqr_handle_interrupt(struct phy_device *phydev)
{
	int irq_status;

	irq_status = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_AN_TX_VEND_INT_STATUS2);
	if (irq_status < 0) {
		phy_error(phydev);
		return IRQ_NONE;
	}

	if (!(irq_status & MDIO_AN_TX_VEND_INT_STATUS2_MASK))
		return IRQ_NONE;

	phy_trigger_machine(phydev);

	return IRQ_HANDLED;
}

So only return IRQ_HANDLED when one of the bits from INT_STATUS
corresponding with the enabled interrupts are set, not if any other link
status bit is set.

Ok, I'll send a v2 with these kind of changes.

Ioana