On Mon, May 06, 2019 at 09:40:19PM +0200, Andrew Lunn wrote:
> On Mon, May 06, 2019 at 07:59:51AM +0300, Mika Westerberg wrote:
> > 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?
>
> Hi Mika
>
> Does that reference the bus as a whole, or a device on the bus?
It references a single device on the bus.
> The SFP subsystem needs a reference to the bus as a whole. There can
> be an at24 like EEPROM at addresses 0x50 and 0x51. There can be an
> MDIO bus encapsulated in i2c at addresses 0x40-0x5f, excluding 0x50
> and 0x51. What actually is there depends on the SFP module which is
> plugged into the SFP cage, and it is all hot-plugable.
Yeah, as I replied on the other email I2CSerialBusV2() cannot really be
used here. I did not realize that the device is referencing the whole bus.
