From: Lukas Wunner <lukas@wunner•de>
To: Florian Fainelli <f.fainelli@gmail•com>
Cc: Marek Szyprowski <m.szyprowski@samsung•com>,
"David S. Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>,
Eric Dumazet <edumazet@google•com>,
netdev@vger•kernel.org, linux-usb@vger•kernel.org,
Steve Glendinning <steve.glendinning@shawell•net>,
UNGLinuxDriver@microchip•com, Oliver Neukum <oneukum@suse•com>,
Andre Edich <andre.edich@microchip•com>,
Oleksij Rempel <linux@rempel-privat•de>,
Martyn Welch <martyn.welch@collabora•com>,
Gabriel Hojda <ghojda@yo2urs•ro>,
Christoph Fritz <chf.fritz@googlemail•com>,
Lino Sanfilippo <LinoSanfilippo@gmx•de>,
Philipp Rosenberger <p.rosenberger@kunbus•com>,
Heiner Kallweit <hkallweit1@gmail•com>,
Andrew Lunn <andrew@lunn•ch>,
Russell King <linux@armlinux•org.uk>,
Ferry Toth <fntoth@gmail•com>,
Krzysztof Kozlowski <krzk@kernel•org>,
'Linux Samsung SOC' <linux-samsung-soc@vger•kernel.org>
Subject: Re: [PATCH net-next v3 5/7] usbnet: smsc95xx: Forward PHY interrupts to PHY driver to avoid polling
Date: Sun, 18 Sep 2022 22:55:16 +0200 [thread overview]
Message-ID: <20220918205516.GA13914@wunner.de> (raw)
In-Reply-To: <d963b1a3-e18d-25d5-f07c-42d17d382174@gmail.com>
On Sun, Sep 18, 2022 at 01:41:13PM -0700, Florian Fainelli wrote:
> On 9/18/2022 12:13 PM, Lukas Wunner wrote:
> > On Mon, Aug 29, 2022 at 01:40:05PM +0200, Marek Szyprowski wrote:
> > > I've finally traced what has happened. I've double checked and indeed
> > > the 1758bde2e4aa commit fixed the issue on next-20220516 kernel and as
> > > such it has been merged to linus tree. Then the commit 744d23c71af3
> > > ("net: phy: Warn about incorrect mdio_bus_phy_resume() state") has been
> > > merged to linus tree, which triggers a new warning during the
> > > suspend/resume cycle with smsc95xx driver. Please note, that the
> > > smsc95xx still works fine regardless that warning. However it look that
> > > the commit 1758bde2e4aa only hide a real problem, which the commit
> > > 744d23c71af3 warns about.
> > >
> > > Probably a proper fix for smsc95xx driver is to call phy_stop/start
> > > during suspend/resume cycle, like in similar patches for other drivers:
> > >
> > > https://lore.kernel.org/all/20220825023951.3220-1-f.fainelli@gmail.com/
> >
> > No, smsc95xx.c relies on mdio_bus_phy_{suspend,resume}() and there's
> > no need to call phy_{stop,start}() >
> > 744d23c71af3 was flawed and 6dbe852c379f has already fixed a portion
> > of the fallout.
> >
> > However the WARN() condition still seems too broad and causes false
> > positives such as in your case. In particular, mdio_bus_phy_suspend()
> > may leave the device in PHY_UP state, so that's a legal state that
> > needs to be exempted from the WARN().
>
> How is that a legal state when the PHY should be suspended? Even if we are
> interrupt driven, the state machine should be stopped, does not mean that
> Wake-on-LAN or other activity interrupts should be disabled.
mdio_bus_phy_suspend()
phy_stop_machine()
phydev->state = PHY_UP # if (phydev->state >= PHY_UP)
So apparently PHY_UP is a legal state for a suspended PHY.
> > Does the issue still appear even after 6dbe852c379f?
> >
> > If it does, could you test whether exempting PHY_UP silences the
> > gratuitous WARN splat? I.e.:
>
> If you allow PHY_UP, then the warning becomes effectively useless, so I
> don't believe this is quite what you want to do here.
Hm, maybe the WARN() should be dropped altogether?
Thanks,
Lukas
next prev parent reply other threads:[~2022-09-18 20:55 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 8:42 [PATCH net-next v3 0/7] Polling be gone on LAN95xx Lukas Wunner
2022-05-12 8:42 ` [PATCH net-next v3 1/7] usbnet: Run unregister_netdev() before unbind() again Lukas Wunner
2022-05-12 8:42 ` [PATCH net-next v3 2/7] usbnet: smsc95xx: Don't clear read-only PHY interrupt Lukas Wunner
2022-05-12 11:57 ` Lukas Wunner
2022-05-12 8:42 ` [PATCH net-next v3 3/7] usbnet: smsc95xx: Don't reset PHY behind PHY driver's back Lukas Wunner
2022-05-12 12:12 ` Lukas Wunner
2022-05-12 8:42 ` [PATCH net-next v3 4/7] usbnet: smsc95xx: Avoid link settings race on interrupt reception Lukas Wunner
2022-05-12 12:15 ` Lukas Wunner
2022-05-12 8:42 ` [PATCH net-next v3 5/7] usbnet: smsc95xx: Forward PHY interrupts to PHY driver to avoid polling Lukas Wunner
2022-05-17 10:18 ` Marek Szyprowski
2022-05-19 19:08 ` Lukas Wunner
2022-05-19 21:22 ` Marek Szyprowski
2022-05-23 9:43 ` Lukas Wunner
2022-05-23 11:38 ` Marek Szyprowski
2022-05-23 12:34 ` Andrew Lunn
2022-05-23 13:47 ` Lukas Wunner
2022-05-24 0:52 ` Andrew Lunn
2022-05-24 1:08 ` Andrew Lunn
2022-05-24 6:16 ` Marek Szyprowski
2022-05-24 12:03 ` Andrew Lunn
2022-05-26 13:55 ` Lukas Wunner
2022-05-24 12:13 ` Lukas Wunner
2022-06-06 1:28 ` Andrew Lunn
2022-08-26 6:51 ` Marek Szyprowski
2022-08-26 7:19 ` Lukas Wunner
2022-08-26 7:41 ` Marek Szyprowski
2022-08-26 7:53 ` Lukas Wunner
2022-08-26 8:29 ` Marek Szyprowski
2022-08-29 11:40 ` Marek Szyprowski
2022-09-18 19:13 ` Lukas Wunner
2022-09-18 20:41 ` Florian Fainelli
2022-09-18 20:55 ` Lukas Wunner [this message]
2022-09-18 22:11 ` Florian Fainelli
2022-09-23 4:20 ` Lukas Wunner
2022-09-22 13:21 ` Marek Szyprowski
2022-05-12 8:42 ` [PATCH net-next v3 6/7] net: phy: smsc: Cache interrupt mask Lukas Wunner
2022-05-12 12:17 ` Lukas Wunner
2022-05-12 8:42 ` [PATCH net-next v3 7/7] net: phy: smsc: Cope with hot-removal in interrupt handler Lukas Wunner
2022-05-12 12:19 ` Lukas Wunner
2022-05-13 10:40 ` [PATCH net-next v3 0/7] Polling be gone on LAN95xx patchwork-bot+netdevbpf
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