Messages in this thread | | | From | Saravana Kannan <> | Date | Tue, 5 Jul 2022 11:57:32 -0700 | Subject | Re: [PATCH net-next v2] net: macb: In shared MDIO usecase make MDIO producer ethernet node to probe first |
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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.
-Saravana
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