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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

  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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