On Mon, Aug 03, 2020 at 02:47:41PM +0000, Madalin Bucur (OSS) wrote: > > -----Original Message----- > > From: Russell King - ARM Linux admin <li...@armlinux.org.uk> > > Sent: 03 August 2020 17:10 > > To: Madalin Bucur (OSS) <madalin.bu...@oss.nxp.com> > > Cc: Andrew Lunn <and...@lunn.ch>; Vikas Singh > > <vikas.si...@puresoftware.com>; f.faine...@gmail.com; hkallwe...@gmail.com; > > netdev@vger.kernel.org; Calvin Johnson (OSS) <calvin.john...@oss.nxp.com>; > > kuldip dwivedi <kuldip.dwiv...@puresoftware.com>; Vikas Singh > > <vikas.si...@nxp.com> > > Subject: Re: [PATCH 2/2] net: phy: Associate device node with fixed PHY > > > > On Mon, Aug 03, 2020 at 11:45:55AM +0000, Madalin Bucur (OSS) wrote: > > > > -----Original Message----- > > > > From: Russell King - ARM Linux admin <li...@armlinux.org.uk> > > > > Sent: 03 August 2020 12:07 > > > > To: Madalin Bucur (OSS) <madalin.bu...@oss.nxp.com> > > > > Cc: Andrew Lunn <and...@lunn.ch>; Vikas Singh > > > > <vikas.si...@puresoftware.com>; f.faine...@gmail.com; > > hkallwe...@gmail.com; > > > > netdev@vger.kernel.org; Calvin Johnson (OSS) > > <calvin.john...@oss.nxp.com>; > > > > kuldip dwivedi <kuldip.dwiv...@puresoftware.com>; Vikas Singh > > > > <vikas.si...@nxp.com> > > > > Subject: Re: [PATCH 2/2] net: phy: Associate device node with fixed > > PHY > > > > > > > > On Mon, Aug 03, 2020 at 08:33:19AM +0000, Madalin Bucur (OSS) wrote: > > > > > > -----Original Message----- > > > > > > From: netdev-ow...@vger.kernel.org <netdev-ow...@vger.kernel.org> > > On > > > > > > Behalf Of Andrew Lunn > > > > > > Sent: 01 August 2020 18:11 > > > > > > To: Russell King - ARM Linux admin <li...@armlinux.org.uk> > > > > > > Cc: Vikas Singh <vikas.si...@puresoftware.com>; > > f.faine...@gmail.com; > > > > > > hkallwe...@gmail.com; netdev@vger.kernel.org; Calvin Johnson (OSS) > > > > > > <calvin.john...@oss.nxp.com>; kuldip dwivedi > > > > > > <kuldip.dwiv...@puresoftware.com>; Madalin Bucur (OSS) > > > > > > <madalin.bu...@oss.nxp.com>; Vikas Singh <vikas.si...@nxp.com> > > > > > > Subject: Re: [PATCH 2/2] net: phy: Associate device node with > > fixed > > > > PHY > > > > > > > > > > > > On Sat, Aug 01, 2020 at 10:41:32AM +0100, Russell King - ARM Linux > > > > admin > > > > > > wrote: > > > > > > > On Sat, Aug 01, 2020 at 09:52:52AM +0530, Vikas Singh wrote: > > > > > > > > Hi Andrew, > > > > > > > > > > > > > > > > Please refer to the "fman" node under > > > > > > > > linux/arch/arm64/boot/dts/freescale/fsl-ls1046a-rdb.dts > > > > > > > > I have two 10G ethernet interfaces out of which one is of > > fixed- > > > > link. > > > > > > > > > > > > > > Please do not top post. > > > > > > > > > > > > > > How does XGMII (which is a 10G only interface) work at 1G speed? > > Is > > > > > > > what is in DT itself a hack because fixed-phy doesn't support > > 10G > > > > > > > modes? > > > > > > > > > > > > My gut feeling is there is some hack going on here, which is why > > i'm > > > > > > being persistent at trying to understand what is actually going on > > > > > > here. > > > > > > > > > > Hi Andrew, > > > > > > > > > > That platform used 1G fixed link there since there was no support > > for > > > > > 10G fixed link at the time. PHYlib could have tolerated 10G speed > > there > > > > > With a one-liner. > > > > > > > > That statement is false. It is not a "one liner". fixed-phy exposes > > > > the settings to userspace as a Clause 22 PHY register set, and the > > > > Clause 22 register set does not support 10G. So, a "one liner" would > > > > just be yet another hack. Adding Clause 45 PHY emulation support > > > > would be a huge task. > > > > > > > > > I understand that PHYLink is working to describe this > > > > > Better, but it was not there at that time. Adding the dependency on > > > > > PHYLink was not desirable as most of the users for the DPAA 1 > > platforms > > > > > were targeting kernels before the PHYLink introduction (and last > > I've > > > > > looked, it's still under development, with unstable APIs so we'll > > > > > take a look at this later, when it settles). > > > > > > > > I think you need to read Documentation/process/stable-api-nonsense.rst > > > > particularly the section "Stable Kernel Source Interfaces". > > > > > > > > phylink is going to be under development for quite some time to come > > > > as requirements evolve. For example, when support for QSFP interfaces > > > > is eventually worked out, I suspect there will need to be some further > > > > changes to the driver interface. This is completely normal. > > > > > > > > Now, as to the stability of the phylink API to drivers, it has in fact > > > > been very stable - it has only changed over the course of this year to > > > > support split PCS, a necessary step for DPAA2 and a few others. It > > has > > > > been around in mainline for two years, and has been around much longer > > > > than that, and during that time it has been in mainline, the MAC > > facing > > > > interface has not changed until recently. > > > > > > > > So, I find your claim to be quite unreasonable. > > > > > > I see you agree that there were and there will be many changes for a > > while, > > > It's not a complaint, I know hot it works, it's just a decision based on > > > required effort vs features offered vs user requirements. Lately it's > > been > > > time consuming to try to fix things in this area. > > > > No, it hasn't been time consuming. The only API changes as far as > > drivers are concerned have been: > > > > 1. the change to the mac_link_up() prototype to move the setup of the > > final link parameters out of mac_config() - and almost all of the > > updates to users were done by me. > > > > 2. the addition of split PCS support, introducing new interfaces, has > > had minimal impact on those drivers that updated in step (1). > > > > There have been no other changes as far as users are concerned. > > > > Some of the difficulty with (1) has been that users of phylink appeared > > initially with no proper review, and consequently they got quite a lot > > wrong. The most common error has been using state->speed, state->duplex > > in mac_config() methods irrespective of the AN mode, which has _always_ > > since before phylink was merged into mainline, been totally unreliable. > > > > That leads me on to the other visible "changes" for users are concerned, > > which may be interpreted as interface changes, but are not; they have > > all been clarifications to the documentation, to strengthen things such > > as "do not use state->speed and state->duplex in mac_config() for > > various specific AN modes". Nothing has actually changed with any of > > those clarifications. > > > > For example, if in in-band mode, and mac_config() uses state->speed > > and state->duplex, then it doesn't matter which version of phylink > > you're using, if someone issues ethtool -s ethN ..., then state->speed > > and state->duplex will be their respective UNKNOWN values, and if you're > > using these in that situation, you will mis-program the MAC. > > > > Again, that is not something that has changed. Ever. But the > > documentation has because people just don't seem to get it, and I seemed > > to be constantly repeating myself in review after review on the same > > points. > > > > So, your assertion that the phylink API is not stable is false. It > > has been remarkably stable over the two years that it has been around. > > It is only natural that as the technology that a piece of code supports > > evolves, so the code evolves with it. That is exactly what has happened > > this year with the two changes I mention above. > > > > Now, if you've found it time consuming to "fix things" (unspecified what > > "things" are) then I assert that what has needed to be fixed are things > > that NXP have got wrong. Such as the rtnl cockups. Such as abusing > > state->speed and state->duplex. None of that is because the interface > > is unstable - they are down to buggy implementation on NXPs part. > > > > Essentially, what I'm saying is that your attempt to paint phylink as > > being painful on the basis of interface changes is totally and utterly > > wrong and is just an excuse to justify abusing the fixed-link code and > > specifying things that are clearly incorrect via DT. > > Thank you for the distilled phylink history, it may be easier to comprehend > with these details. I was not referring to phylink, but PHY related issues > on the DPAA 1 platforms.
Sigh. No, you were referring to phylink. This is what you said: > I understand that PHYLink is working to describe this > Better, but it was not there at that time. Adding the dependency on > PHYLink was not desirable as most of the users for the DPAA 1 platforms > were targeting kernels before the PHYLink introduction (and last I've > looked, it's still under development, with unstable APIs so we'll > take a look at this later, when it settles). This discussion stems from your misconception and incorrect statements concerning phylink, which I am correcting in this discussion. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
