From: Florian Fainelli <f.fainelli@gmail.com>
To: Saravana Kannan <saravanak@google.com>
Cc: Andrew Lunn <andrew@lunn.ch>, Vladimir Oltean <olteanv@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Vivien Didelot <vivien.didelot@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Len Brown <lenb@kernel.org>,
Alvin Sipraga <ALSI@bang-olufsen.dk>,
kernel-team@android.com, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: [PATCH v1 1/2] driver core: fw_devlink: Add support for FWNODE_FLAG_BROKEN_PARENT
Date: Thu, 30 Sep 2021 14:16:06 -0700 [thread overview]
Message-ID: <2be871eb-d6e1-965c-d268-dc146bee54d3@gmail.com> (raw)
In-Reply-To: <CAGETcx_G3haECnv-FS4L16PCmpfbCB3hhqHssT2E8d1fw5D3zw@mail.gmail.com>
On 9/30/21 1:14 PM, Saravana Kannan wrote:
> On Thu, Sep 30, 2021 at 1:06 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>>
>> On 9/30/21 12:48 PM, Saravana Kannan wrote:
>>> On Thu, Sep 30, 2021 at 12:38 PM Andrew Lunn <andrew@lunn.ch> wrote:
>>>>
>>>>> Btw, do we have non-DSA networking devices where fw_devlink=on
>>>>> delaying PHY probes is causing an issue?
>>>>
>>>> I don't know if issues have been reported, but the realtek driver has
>>>> had problems in the past when the generic driver is used. Take a look
>>>> at r8169_mdio_register(), it does something similar to DSA.
>>>
>>> Does it have the issue of having the PHY as its child too and then
>>> depending on it to bind to a driver? I can't tell because I didn't
>>> know how to find that info for a PCI device.
>>
>> Yes, r8169 includes a MDIO bus controller, and the PHY is internal to
>> the Ethernet MAC. These are AFAIR the relevant changes to this discussion:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=16983507742cbcaa5592af530872a82e82fb9c51
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=11287b693d03830010356339e4ceddf47dee34fa
>>
>>
>>>
>>>>
>>>> What is going to make things interesting is that phy_attach_direct()
>>>> is called in two different contexts. During the MAC drivers probe, it
>>>> is O.K. to return EPROBE_DEFER, and let the MAC driver try again
>>>> later, if we know there is a specific PHY driver for it. But when
>>>> called during the MAC drivers open() op, -EPROBE_DEFER is not
>>>> allowed. What to do then is an interesting question.
>>>
>>> Yeah, basically before doing an open() it'll have to call an API to
>>> say "just bind with whatever you got". Or something along those lines.
>>> I already know how to get that to work. I'll send some RFC soonish (I
>>> hope).
>>
>> I don't think this is going to scale, we have dozens and dozens of
>> drivers that connect to the PHY during ndo_open().
>
> Whichever code calls ->ndo_open() can't that mark all the PHYs that'll
> be used as "needs to be ready now"? In any case, if we can have an API
> that allows a less greedy Generic PHY binding, we could slowly
> transition drivers over or at least move them over as they hit issues
> with Gen PHY. Anyway, I'll think discussing it over code would be
> easier. I'll also have more context as I try to make changes. So,
> let's continue this on my future RFC.
It is the same API that is being used whether you connect to the PHY at
ndo_open() time or whether you do that during the parent's ->probe()
fortunately or unfortunately. Now we could set a flag in either case,
and hope that it addresses both situations?
Being able to be selective about the Ethernet PHY driver is being used
is actually a good idea, there are plenty of systems out there whereby
using the Generic PHY driver will not lead to a functional Ethernet
link, if we could say "I want my dedicated driver, and not Generic PHY"
that would actually help some cases, too.
--
Florian
next prev parent reply other threads:[~2021-09-30 21:16 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 7:45 [PATCH v1 0/2] Fix rtl8366rb issues with fw_devlink=on Saravana Kannan
2021-08-26 7:45 ` [PATCH v1 1/2] driver core: fw_devlink: Add support for FWNODE_FLAG_BROKEN_PARENT Saravana Kannan
2021-08-26 13:13 ` Andrew Lunn
2021-08-26 19:56 ` Saravana Kannan
2021-08-26 20:53 ` Andrew Lunn
2021-08-26 23:44 ` Saravana Kannan
2021-08-27 1:23 ` Andrew Lunn
2021-08-27 4:02 ` Saravana Kannan
2021-08-27 13:44 ` Andrew Lunn
2021-08-27 18:06 ` Saravana Kannan
2021-08-27 20:11 ` Andrew Lunn
2021-08-27 21:33 ` Saravana Kannan
2021-08-28 17:01 ` Andrew Lunn
2021-08-30 19:03 ` Saravana Kannan
2021-08-31 13:16 ` Andrew Lunn
2021-08-31 19:26 ` Saravana Kannan
2021-08-31 22:05 ` Andrew Lunn
2021-08-31 22:18 ` Saravana Kannan
2021-08-31 23:02 ` Andrew Lunn
2021-08-31 23:18 ` Vladimir Oltean
2021-08-31 23:27 ` Andrew Lunn
2021-09-01 1:28 ` Vladimir Oltean
2021-09-01 1:38 ` Vladimir Oltean
2021-09-01 2:19 ` Saravana Kannan
2021-09-01 9:02 ` Vladimir Oltean
2021-09-01 22:57 ` Saravana Kannan
2021-09-01 2:00 ` Saravana Kannan
2021-09-01 8:46 ` Vladimir Oltean
2021-09-01 22:53 ` Saravana Kannan
2021-09-02 17:41 ` Andrew Lunn
2021-09-02 17:58 ` Saravana Kannan
2021-09-30 5:33 ` Saravana Kannan
2021-09-30 13:15 ` Andrew Lunn
2021-09-30 13:43 ` Vladimir Oltean
2021-09-30 14:00 ` Andrew Lunn
2021-09-30 17:31 ` Saravana Kannan
2021-09-30 19:38 ` Andrew Lunn
2021-09-30 19:48 ` Saravana Kannan
2021-09-30 20:06 ` Florian Fainelli
2021-09-30 20:14 ` Saravana Kannan
2021-09-30 21:16 ` Florian Fainelli [this message]
2021-09-30 20:22 ` Andrew Lunn
2021-09-01 1:46 ` Saravana Kannan
2021-08-31 23:18 ` Andrew Lunn
2021-09-08 18:35 ` Saravana Kannan
2021-09-09 1:39 ` Andrew Lunn
2021-09-09 3:21 ` Saravana Kannan
2021-09-09 10:38 ` Vladimir Oltean
2021-09-09 15:00 ` Andrew Lunn
2021-09-09 16:56 ` Florian Fainelli
2021-08-26 7:45 ` [PATCH v1 2/2] net: dsa: rtl8366rb: Quick fix to work with fw_devlink=on Saravana Kannan
2021-08-26 7:55 ` Greg Kroah-Hartman
2021-08-26 11:25 ` Florian Fainelli
2021-08-26 17:29 ` Saravana Kannan
2021-08-26 11:29 ` Alvin Šipraga
2021-08-26 17:26 ` Saravana Kannan
2021-08-26 18:04 ` Alvin Šipraga
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