linux-kernel - Re: [PATCH 4/5] net: phy: marvell: Add LED accessors for Marvell 88E1510

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Date:   Thu, 21 Apr 2022 20:24:00 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     hkallweit1@...il.com, linux@...linux.org.uk,
        peppe.cavallaro@...com, alexandre.torgue@...s.st.com,
        joabreu@...opsys.com, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] net: phy: marvell: Add LED accessors for Marvell 88E1510

On Thu, Apr 21, 2022 at 7:51 PM Andrew Lunn <andrew@...n.ch> wrote:
>
> > This is not feasible.
> > If BIOS can define a method and restore the LED by itself, it can put
> > the method inside its S3 method and I don't have to work on this at
> > the first place.
>
> So maybe just declare the BIOS as FUBAR and move on to the next issue
> assigned to you.
>
> Do we really want the maintenance burden of this code for one machines
> BIOS?

Wasn't this the "set precedence" we discussed earlier for? Someone has
to be the first, and more users will leverage the new property we
added.

> Maybe the better solution is to push back on the vendor and its
> BIOS, tell them how they should of done this, if the BIOS wants to be
> in control of the LEDs it needs to offer the methods to control the
> LEDs. And then hopefully the next machine the vendor produces will
> have working BIOS.

The BIOS doesn't want to control the LED. It just provides a default
LED setting suitable for this platform, so the driver can use this
value over the hardcoded one in marvell phy driver.
So this really has nothing to do with with any ACPI method.
I believe the new property can be useful for DT world too.

>
> Your other option is to take part in the effort to add control of the
> LEDs via the standard Linux LED subsystem. The Marvel PHY driver is
> likely to be one of the first to gain support this for. So you can
> then totally take control of the LED from the BIOS and put it in the
> users hands. And such a solution will be applicable to many machines,
> not just one.

This series just wants to use the default value platform firmware provides.
Create a sysfs to let user meddle with LED value doesn't really help
the case here.

Kai-Heng

>
>        Andrew