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

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Message-ID: <fee0997d-f4bc-dfc3-9423-476f04218614@gmail.com>
Date:   Sat, 31 Oct 2020 11:18:18 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     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 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.

> For example code, what is listed above is O.K. The real implementation
> in a driver need knowledge of the hardware.
> 
>       Andrew
> .
> 
Heiner