Re: [PATCH 2/2] net: dsa: microchip: Provide Module 4 KSZ9477 errata (DS80000754C)

[Florian Fainelli]

On 8/29/23 14:57, Tristram.Ha@xxxxxxxxxxxxx wrote:
> > On Fri, Aug 25, 2023 at 06:48:41PM +0000, Tristram.Ha@xxxxxxxxxxxxx wrote:
> > > > > IMHO adding functions to MMD modification would facilitate further
> > > > > development (for example LED setup).
> > > >
> > > > We already have some KSZ9477 specific initialization done in the Micrel
> > > > PHY driver under drivers/net/phy/micrel.c, can we converge on the PHY
> > > > driver which has a reasonable amount of infrastructure for dealing with
> > > > workarounds, indirect or direct MMD accesses etc.?
> > >
> > > Actually the internal PHY used in the KSZ9897/KSZ9477/KSZ9893 switches
> > > are special and only used inside those switches.  Putting all the switch
> > > related code in Micrel PHY driver does not really help.  When the switch
> > > is reset all those PHY registers need to be set again, but the PHY driver
> > > only executes those code during PHY initialization.  I do not know if
> > > there is a good way to tell the PHY to re-initialize again.
> >
> > Suppose there was a method to tell the PHY driver to re-initialize itself.
> > What would be the key points in which the DSA switch driver would need
> > to trigger that method? Where is the switch reset at runtime?
>
> Currently the DSA switch driver loads independently and is then
> controlled by the main DSA driver.  The switch is reset during
> initialization, and later the PHYs are initialized.  I was talking
> hypothetically that the switch may need to be reset to correct some
> hardware problems, but then there may be no good way to tell the PHYs to
> re-initialize.

There is phy_init_hw() which will do just that.
--
Florian