From: Florian Fainelli <f.fainelli@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>,
"Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: "Vladimir Oltean" <vladimir.oltean@nxp.com>,
netdev@vger.kernel.org,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
"Jakub Kicinski" <kuba@kernel.org>,
"Vivien Didelot" <vivien.didelot@gmail.com>,
"Vladimir Oltean" <olteanv@gmail.com>,
linux-kernel@vger.kernel.org,
"Linus Walleij" <linus.walleij@linaro.org>,
"Alvin Šipraga" <alsi@bang-olufsen.dk>,
"ACPI Devel Maling List" <linux-acpi@vger.kernel.org>,
kernel-team <kernel-team@android.com>,
"Len Brown" <lenb@kernel.org>
Subject: Re: [RFC PATCH net-next 1/3] net: phy: don't bind genphy in phy_attach_direct if the specific driver defers probe
Date: Thu, 2 Sep 2021 13:33:57 -0700 [thread overview]
Message-ID: <bd7c9398-5d3d-ccd8-8804-25074cff6bde@gmail.com> (raw)
In-Reply-To: <YTErTRBnRYJpWDnH@lunn.ch>
On 9/2/2021 12:51 PM, Andrew Lunn wrote:
> On Thu, Sep 02, 2021 at 07:50:16PM +0100, Russell King (Oracle) wrote:
>> On Thu, Sep 02, 2021 at 01:50:51AM +0300, Vladimir Oltean wrote:
>>> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
>>> index 52310df121de..2c22a32f0a1c 100644
>>> --- a/drivers/net/phy/phy_device.c
>>> +++ b/drivers/net/phy/phy_device.c
>>> @@ -1386,8 +1386,16 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
>>>
>>> /* Assume that if there is no driver, that it doesn't
>>> * exist, and we should use the genphy driver.
>>> + * The exception is during probing, when the PHY driver might have
>>> + * attempted a probe but has requested deferral. Since there might be
>>> + * MAC drivers which also attach to the PHY during probe time, try
>>> + * harder to bind the specific PHY driver, and defer the MAC driver's
>>> + * probing until then.
>>> */
>>> if (!d->driver) {
>>> + if (device_pending_probe(d))
>>> + return -EPROBE_DEFER;
>>
>> Something else that concerns me here.
>>
>> As noted, many network drivers attempt to attach their PHY when the
>> device is brought up, and not during their probe function.
>
> Yes, this is going to be a problem. I agree it is too late to return
> -EPROBE_DEFER. Maybe phy_attach_direct() needs to wait around, if the
> device is still on the deferred list, otherwise use genphy. And maybe
> a timeout and return -ENODEV, which is not 100% correct, we know the
> device exists, we just cannot drive it.
Is it really going to be a problem though? The two cases where this will
matter is if we use IP auto-configuration within the kernel, which this
patchset ought to be helping with, if we are already in user-space and
the PHY is connected at .ndo_open() time, there is a whole lot of things
that did happen prior to getting there, such as udevd using modaliases
in order to load every possible module we might, so I am debating
whether we will really see a probe deferral at all.
>
> Can we tell we are in the context of a driver probe? Or do we need to
> add a parameter to the various phy_attach API calls to let the core
> know if this is probe or open?
Actually we do the RTNL lock will be held during ndo_open and it won't
during driver probe.
>
> This is more likely to be a problem with NFS root, with the kernel
> bringing up an interface as soon as its registered. userspace bringing
> up interfaces is generally much later, and udev tends to wait around
> until there are no more driver load requests before the boot
> continues.
See my point above, with Vladimir's change, we should have fw_devlink do
its job such that by the time the network interface is needed for IP
auto-configuration, all of its depending resources should also be ready,
would not they?
--
Florian
next prev parent reply other threads:[~2021-09-02 20:34 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 22:50 [RFC PATCH net-next 0/3] Make the PHY library stop being so greedy when binding the generic PHY driver Vladimir Oltean
2021-09-01 22:50 ` [RFC PATCH net-next 1/3] net: phy: don't bind genphy in phy_attach_direct if the specific driver defers probe Vladimir Oltean
2021-09-02 5:43 ` Greg Kroah-Hartman
2021-09-02 10:11 ` Vladimir Oltean
2021-09-02 10:37 ` Greg Kroah-Hartman
2021-09-02 11:17 ` Vladimir Oltean
2021-09-02 14:37 ` Rafael J. Wysocki
2021-09-02 18:50 ` Russell King (Oracle)
2021-09-02 19:23 ` Vladimir Oltean
2021-09-02 19:51 ` Andrew Lunn
2021-09-02 20:33 ` Florian Fainelli [this message]
2021-09-02 21:33 ` Russell King (Oracle)
2021-09-02 21:39 ` Vladimir Oltean
2021-09-02 22:24 ` Russell King (Oracle)
2021-09-02 22:45 ` Vladimir Oltean
2021-09-02 23:02 ` Andrew Lunn
2021-09-02 23:26 ` Vladimir Oltean
2021-09-03 0:04 ` Russell King (Oracle)
2021-09-03 20:48 ` Vladimir Oltean
2021-09-03 22:06 ` Russell King (Oracle)
2021-09-04 21:59 ` Vladimir Oltean
2021-09-04 23:25 ` Russell King (Oracle)
2021-09-05 0:41 ` Vladimir Oltean
2021-09-03 9:27 ` Ioana Ciornei
2021-09-01 22:50 ` [RFC PATCH net-next 2/3] net: dsa: destroy the phylink instance on any error in dsa_slave_phy_setup Vladimir Oltean
2021-09-02 12:25 ` Russell King (Oracle)
2021-09-02 23:21 ` Florian Fainelli
2021-09-01 22:50 ` [RFC PATCH net-next 3/3] net: dsa: allow the phy_connect() call to return -EPROBE_DEFER Vladimir Oltean
2021-09-02 12:19 ` [RFC PATCH net-next 0/3] Make the PHY library stop being so greedy when binding the generic PHY driver Russell King (Oracle)
2021-09-02 12:35 ` Vladimir Oltean
2021-09-02 12:59 ` Vladimir Oltean
2021-09-02 13:26 ` Russell King (Oracle)
2021-09-02 15:23 ` Vladimir Oltean
2021-09-02 16:31 ` Russell King (Oracle)
2021-09-02 17:10 ` Vladimir Oltean
2021-09-02 17:50 ` Russell King (Oracle)
2021-09-02 19:05 ` Vladimir Oltean
2021-09-02 20:03 ` Russell King (Oracle)
2021-09-02 20:21 ` Vladimir Oltean
2021-09-02 20:29 ` Russell King (Oracle)
2021-09-03 16:22 ` Vladimir Oltean
2021-09-03 17:21 ` Andrew Lunn
2021-09-03 18:58 ` Russell King (Oracle)
2021-09-03 19:56 ` Andrew Lunn
2021-09-03 20:08 ` Russell King (Oracle)
2021-09-03 18:54 ` Russell King (Oracle)
2021-09-03 20:11 ` Vladimir Oltean
2021-09-02 20:07 ` Andrew Lunn
2021-09-02 20:32 ` Vladimir Oltean
2021-09-02 21:39 ` Russell King (Oracle)
2021-09-02 22:05 ` Vladimir Oltean
2021-09-02 23:29 ` Saravana Kannan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bd7c9398-5d3d-ccd8-8804-25074cff6bde@gmail.com \
--to=f.fainelli@gmail.com \
--cc=alsi@bang-olufsen.dk \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=gregkh@linuxfoundation.org \
--cc=hkallweit1@gmail.com \
--cc=kernel-team@android.com \
--cc=kuba@kernel.org \
--cc=lenb@kernel.org \
--cc=linus.walleij@linaro.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=netdev@vger.kernel.org \
--cc=olteanv@gmail.com \
--cc=rafael@kernel.org \
--cc=vivien.didelot@gmail.com \
--cc=vladimir.oltean@nxp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).