Messages in this thread | | | From | "Pandey, Radhey Shyam" <> | Subject | RE: [PATCH net-next v2] net: macb: In shared MDIO usecase make MDIO producer ethernet node to probe first | Date | Fri, 15 Jul 2022 19:00:12 +0000 |
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> -----Original Message----- > From: Saravana Kannan <saravanak@google.com> > Sent: Wednesday, July 6, 2022 12:28 AM > To: Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com> > Cc: Andrew Lunn <andrew@lunn.ch>; nicolas.ferre@microchip.com; > claudiu.beznea@microchip.com; davem@davemloft.net; > edumazet@google.com; kuba@kernel.org; pabeni@redhat.com; > hkallweit1@gmail.com; linux@armlinux.org.uk; > gregkh@linuxfoundation.org; rafael@kernel.org; netdev@vger.kernel.org; > linux-kernel@vger.kernel.org; git (AMD-Xilinx) <git@amd.com> > Subject: Re: [PATCH net-next v2] net: macb: In shared MDIO usecase make > MDIO producer ethernet node to probe first > > On Tue, Jul 5, 2022 at 11:49 AM Pandey, Radhey Shyam > <radhey.shyam.pandey@amd.com> wrote: > > > > > -----Original Message----- > > > From: Andrew Lunn <andrew@lunn.ch> > > > Sent: Friday, July 1, 2022 2:44 PM > > > To: Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com> > > > Cc: nicolas.ferre@microchip.com; claudiu.beznea@microchip.com; > > > davem@davemloft.net; edumazet@google.com; kuba@kernel.org; > > > pabeni@redhat.com; hkallweit1@gmail.com; linux@armlinux.org.uk; > > > gregkh@linuxfoundation.org; rafael@kernel.org; > saravanak@google.com; > > > netdev@vger.kernel.org; linux-kernel@vger.kernel.org; git > > > (AMD-Xilinx) <git@amd.com> > > > Subject: Re: [PATCH net-next v2] net: macb: In shared MDIO usecase > > > make MDIO producer ethernet node to probe first > > > > > > On Fri, Jul 01, 2022 at 01:25:06AM +0530, Radhey Shyam Pandey wrote: > > > > In shared MDIO suspend/resume usecase for ex. with MDIO producer > > > > (0xff0c0000) eth1 and MDIO consumer(0xff0b0000) eth0 there is a > > > > constraint that ethernet interface(ff0c0000) MDIO bus producer has > > > > to be resumed before the consumer ethernet interface(ff0b0000). > > > > > > > > However above constraint is not met when GEM0(ff0b0000) is resumed > first. > > > > There is phy_error on GEM0 and interface becomes non-functional on > > > resume. > > > > > > > > suspend: > > > > [ 46.477795] macb ff0c0000.ethernet eth1: Link is Down [ > > > > 46.483058] macb ff0c0000.ethernet: gem-ptp-timer ptp clock > unregistered. > > > > [ 46.490097] macb ff0b0000.ethernet eth0: Link is Down [ > > > > 46.495298] macb ff0b0000.ethernet: gem-ptp-timer ptp clock > unregistered. > > > > > > > > resume: > > > > [ 46.633840] macb ff0b0000.ethernet eth0: configuring for > > > > phy/sgmii link mode macb_mdio_read -> pm_runtime_get_sync(GEM1) > it > > > > return - > > > EACCES error. > > > > > > > > The suspend/resume is dependent on probe order so to fix this > > > > dependency ensure that MDIO producer ethernet node is always > > > > probed first followed by MDIO consumer ethernet node. > > > > > > > > During MDIO registration find out if MDIO bus is shared and check > > > > if MDIO producer platform node(traverse by 'phy-handle' property) > > > > is bound. If not bound then defer the MDIO consumer ethernet node > probe. > > > > Doing it ensures that in suspend/resume MDIO producer is resumed > > > > followed by MDIO consumer ethernet node. > > > > > > I don't think there is anything specific to MACB here. There are > > > Freescale boards which have an MDIO bus shared by two interfaces etc. > > > > > > Please try to solve this in a generic way, not specific to one MAC > > > and MDIO combination. > > > > Thanks for the review. I want to get your thoughts on the outline of > > the generic solution. Is the current approach fine and we can extend > > it for all shared MDIO use cases/ or do we see any limitations? > > > > a) Figure out if the MDIO bus is shared. (new binding or reuse > > existing) > > b) If the MDIO bus is shared based on DT property then figure out if > > the MDIO producer platform device is probed. If not, defer MDIO > > consumer MDIO bus registration. > > Radhey, > > I think Andrew added me because he's pointing you towards fw_devlink. > > Andrew, > > I have intentionally not added phy-handle support to fw_devlink because it > would also prevent the generic driver from binding/cause issues with DSA. I > have some high level ideas on fixing that but haven't gotten around to it yet. Thanks, just want to understand on implementation when phy-handle support is added to fw_devlink. Does it ensure that supplier node is probed first? Or it uses device_link framework to specify suspend/resume dependency and don't care on consumer/producer probe order.
> > -Saravana
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