linux-kernel - Re: [PATCH net-next 2/2] net: phy: sfp: enable i2c-bus detection on ACPI based systems

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Message-ID: <20190507092946.GS2895@lahna.fi.intel.com>
Date:   Tue, 7 May 2019 12:29:46 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Ruslan Babayev <ruslan@...ayev.com>
Cc:     linux@...linux.org.uk, andrew@...n.ch, f.fainelli@...il.com,
        hkallweit1@...il.com, wsa@...-dreams.de, davem@...emloft.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-acpi@...r.kernel.org,
        xe-linux-external@...co.com
Subject: Re: [PATCH net-next 2/2] net: phy: sfp: enable i2c-bus detection on
 ACPI based systems

On Mon, May 06, 2019 at 11:14:15AM -0700, Ruslan Babayev wrote:
> 
> Mika Westerberg writes:
> 
> > On Sun, May 05, 2019 at 03:05:23PM -0700, Ruslan Babayev wrote:
> >> Lookup I2C adapter using the "i2c-bus" device property on ACPI based
> >> systems similar to how it's done with DT.
> >> 
> >> An example DSD describing an SFP on an ACPI based system:
> >> 
> >> Device (SFP0)
> >> {
> >>     Name (_HID, "PRP0001")
> >>     Name (_DSD, Package ()
> >>     {
> >>         ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> >>         Package () {
> >>             Package () { "compatible", "sff,sfp" },
> >>             Package () { "i2c-bus", \_SB.PCI0.RP01.I2C.MUX.CH0 },
> >
> > Hmm, ACPI has I2cSerialBusV2() resource for this purpose. Why you are not
> > using that?
> 
> I am not an ACPI expert, but my understanding is I2cSerialBusV2() is
> used for slave connections. I am trying to reference an I2C controller
> here.

Ah, the device itself is not sitting on an I2C bus? In that case I
agree, I2CSerialBusV2() is not correct here.