Messages in this thread | | | From | Tim Harvey <> | Date | Thu, 3 Feb 2022 08:02:49 -0800 | Subject | Re: [PATCH net v3] net: phy: intel-xway: enable integrated led functions |
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On Wed, Feb 2, 2022 at 7:12 PM Florian Fainelli <f.fainelli@gmail.com> wrote: > > > > On 2/2/2022 5:01 PM, Andrew Lunn wrote: > >> As a person responsible for boot firmware through kernel for a set of > >> boards I continue to do the following to keep Linux from mucking with > >> various PHY configurations: > >> - remove PHY reset pins from Linux DT's to keep Linux from hard resetting PHY's > >> - disabling PHY drivers > >> > >> What are your thoughts about this? > > > > Hi Tim > > > > I don't like the idea that the bootloader is controlling the hardware, > > not linux. > > This is really trying to take advantage of the boot loader setting > things up in a way that Linux can play dumb by using the Generic PHY > driver and being done with it. This works... until it stops, which > happens very very quickly in general. The perfect counter argument to > using the Generic PHY driver is when your system implements a low power > mode where the PHY loses its power/settings, comes up from suspend and > the strap configuration is insufficient and the boot loader is not part > of the resume path *prior* to Linux. In that case Linux needs to restore > the settings, but it needs a PHY driver for that.
Florian,
That makes sense - I'm always trying to figure out what the advantage of using some of these PHY drivers really is vs disabling them.
> > If your concern Tim is with minimizing the amount of time the link gets > dropped and re-established, then there is not really much that can be > done that is compatible with Linux setting things up, short of > minimizing the amount of register writes that do need the "commit phase" > via BMCR.RESET.
No, my reasoning has nothing to do with link time - I have just run into several cases where some new change in a PHY driver blatantly either resets the PHY reverting to pin-strapping config which is wrong (happend to me with DP83867 but replacing the 'reset' to a 'restart' solved that) or imposes some settings without dt bindings to guide it (this case with the LEDs) or imposes some settings based on 'new' dt-bindings which I was simply not aware of (a lesser issue as dt bindings can be added to resolve it).
> > I do agree that blindly imposing LED settings that are different than > those you want is not great, and should be remedied. Maybe you can > comment this part out in your downstream tree for a while until the LED > binding shows up (we have never been so close I am told).
or disable the driver in defconfig, or blacklist the module if I want to do it via rootfs.
Can you point me to something I can look at for these new LED bindings that are being worked on?
Best Regards,
Tim
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