[U-Boot] [PATCH v5 6/7] phy: Add USB PHY driver for the cadence USB3

Peter Chen peter.chen at nxp.com
Thu Aug 29 03:16:30 UTC 2019

> >
> > This is indeed a different driver. IMO it would be better to keep the
> > driver closer to its linux version. The reason for that  is that it is
> > quite new and will be adapted when platforms starts supporting it. If
> > we start with something too far from the original, it will hard to update.
> > Already I see that the registers initialized are not all the same as
> > in the linux driver and not all the values are the same either, nor
> > are the register names
> >
> > TI's J7 platforms is using this PHY driver for USB3/PCIe support, and
> > the linux driver has already seen quite a few modifications to get it
> > to work
> (https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.ti.
> > com%2Fti-linux-kernel%2Fti-linux-kernel%2Fblobs%2Fhistory%2Fti-linux-
> > 4.19.y%2Fdrivers%2Fphy%2Fcadence%2Fphy-cadence-
> > sierra.c&data=02%7C01%7Csherry.sun%40nxp.com%7C84f9122d7eb64
> > 9820bae08d72b997681%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0
> > %7C637025810458595586&sdata=6JpD7VcFudhzXSVP0WaGVEp7Fwrue
> > A%2B4V6eeOfif19w%3D&reserved=0)
> > Adding support for it on top of this current version will be rather difficult.
> >
> Thanks for your advice.
> Actually I am not familiar with this phy driver in linux, so also +peter, who worked on
> this USB driver under linux, maybe he can give some suggestions.

Add Alan from Cadence

Alan, we find the suggested value at this driver (drivers/phy/cadence/phy-cadence-sierra.c)
is so different with "USB 3.0 PHY User Guide for 28FDSOI" CH 3.1.1 Bring-up Sequence.
Does this driver support this 28nm PHY? If it supports, why the initialized value is so different?
The UG suggested value can be used at NXP platform.


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