Re: [PATCH v2 2/6] net: phy: broadcom: Add BCM54810 PHY entry

Jon Mason
2016-11-01T16:00:13Z

On Sat, Oct 29, 2016 at 10:18:39AM +0200, Andrew Lunn wrote:
> On Fri, Oct 28, 2016 at 04:56:55PM -0400, Jon Mason wrote:
> > The BCM54810 PHY requires some semi-unique configuration, which results
> > in some additional configuration in addition to the standard config.
> > Also, some users of the BCM54810 require the PHY lanes to be swapped.
> > Since there is no way to detect this, add a device tree query to see if
> > it is applicable.
> >
> > Inspired-by: Vikas Soni <vsoni@broadcom.com>
> > Signed-off-by: Jon Mason <jon.mason@broadcom.com>
> > ---
> > drivers/net/phy/Kconfig | 2 +-
> > drivers/net/phy/broadcom.c | 58 +++++++++++++++++++++++++++++++++++++++++++++-
> > include/linux/brcmphy.h | 10 ++++++++
>
> Hi Jon
>
> The binding documentation is missing.
>
> > + if (of_property_read_bool(np, "brcm,enet-phy-lane-swap")) {
> > + /* Lane Swap - Undocumented register...magic! */
> > + ret = bcm_phy_write_exp(phydev, MII_BCM54XX_EXP_SEL_ER + 0x9,
> > + 0x11B);
> > + if (ret < 0)
> > + return ret;
> > + }
> > +
>
> I wounder if this property could be made generic? What exactly are you
> swapping? Rx and Tx lanes? Maybe we should add it to phy.txt?

Are you envisioning adding a DT check (similar to the
of_property_read_bool above, only with a more generic string) in
phy_device_create(), which will then set a PHY device flag? This flag
would then be checked for in the PHY driver and the appropriate action
taken (in this case the bcm_phy_write_exp above).

If so, I cam completely fine doing this. I think the only caveat
would be that this would be creating a generic interface for only 1
user. If you envision this being used by others, then disregard my
concern.

Thanks,
Jon

>
> Andrew