[U-Boot] [PATCH v2 1/4] udoo: Add ethernet support (FEC + Micrel KSZ9031).

[Giuseppe Pagano <giuseppe.pagano@seco.com>]

Hi Stefano,

On Mon, 2013-11-18 at 16:51 +0100, Stefano Babic wrote:
> Hi Giuseppe,
> 
> On 15/11/2013 17:42, Giuseppe Pagano wrote:
> > Add Ethernet and networking support on uDoo board (FEC +phy Micrel KSZ9031).
> > Ethernet speed is currently limited to 10/100Mbps.
> > 
> > Signed-off-by: Giuseppe Pagano <giuseppe.pagano@seco.com>
> > Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
> > CC: Stefano Babic <sbabic@denx.de>
> > CC: Fabio Estevam <fabio.estevam@freescale.com>
> > ---
> 
> IMHO the patch is ok. If there are not any further comments, I mark your
> patchset for merging.

good!

> 
> > +	ksz9031_phy_extended_write(phydev, 0x02,
> > +				   MII_KSZ9031_EXT_RGMII_CLOCK_SKEW,
> > +				   MII_KSZ9031_MOD_DATA_NO_POST_INC, 0x03FF);
> 
> I had also some issues with KSZ9031 and i.MX6. Gigabit starts working
> only after setting the clock skew. I see you set the register again with
> the default value (0x3FF). Because it is the reset value, it is not
> required to set it again, but more important : have you make a trying
> enabling Gb and adjusting only this extended register ? Rather the
> KSZ9031's manual is not clear and does not say a lot about it,

I have september 2012 revision of KSZ9031's manual, and I think it is
complete enough about skew parameter (preliminary version was not). 
Default value for GTX_CLK and RX_CLK swek register is 0x001ef (0 ns
delay for both). I use maximum positive delay (value 0x03ff) as safe
value, but it doesn't work on every board. I also tested halfway value
and negative delay, but again this value doesn't works on every board I
tested. 
Linux kernel, with the same skew configuration for data and clock, works
well with Gigabit ! I've marked as to do to understand why Gigabit works
under Linux, and not with u-boot.  

> 
> Best regards,
> Stefano Babic
> 

Best regards
Giuseppe Pagano