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Date: Tue, 6 Oct 2020 14:11:48 -0700 From: Florian Fainelli <f.fainelli@...il.com> To: Marek Vasut <marex@...x.de>, Oleksij Rempel <o.rempel@...gutronix.de>, Andrew Lunn <andrew@...n.ch> Cc: David Jander <david@...tonic.nl>, kernel@...gutronix.de, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, Russell King <linux@...linux.org.uk>, mkl@...gutronix.de Subject: Re: PHY reset question On 10/6/2020 1:24 PM, Marek Vasut wrote: > On 10/6/20 9:36 PM, Florian Fainelli wrote: > [...] >>> - Use compatible ("compatible = "ethernet-phy-id0022.1560") in the >>> devicetree, >>> so that reading the PHYID is not needed >>> - easy to solve. >>> Disadvantage: >>> - losing PHY auto-detection capability >>> - need a new devicetree if different PHY is used (for example in >>> different >>> board revision) >> >> Or you can punt that to the boot loader to be able to tell the >> difference and populate different compatible, or even manage the PHY >> reset to be able to read the actual PHY OUI. To me that is still the >> best solution around. > > Wasn't there some requirement for Linux to be bootloader-independent ? What kind of dependency does this create here? The fact that Linux is capable of parsing a compatible string of the form "ethernet-phyAAAA.BBBB" is not something that is exclusively applicable to Linux. Linux just so happens to support that, but so could FreeBSD or any OS for that matter. This is exactly the way firmware should be going, that is to describe accurately the hardware, while making the life of the OS much easier when it can. If we supported ACPI that is exactly what would have to happen IMHO. > Some systems cannot replace their bootloaders, e.g. if the bootloader is > in ROM, so this might not be a solution. It is always possible to chain load a field updateable boot loader, and even when that is not desirable you could devise a solution that allows to utilize say a slightly different DTB that you could append to the kernel. Again, if you want to use strictly the same DTB, then you have to do what I just suggested and have the boot loader absorb some of this complexit > >>> - modify PHY framework to deassert reset before identifying the PHY. >>> Disadvantages? > > If this happens on MX6 with FEC, can you please try these two patches? > > https://patchwork.ozlabs.org/project/netdev/patch/20201006135253.97395-1-marex@denx.de/ > > https://patchwork.ozlabs.org/project/netdev/patch/20201006202029.254212-1-marex@denx.de/ Your patches are not scaling across multiple Ethernet MAC drivers unfortunately, so I am not sure this should be even remotely considered a viable solution. -- Florian
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