Re: [RFC][PATCH] PowerPC 4xx: ibm_newemac 440GX phy clock workaround.

[Josh Boyer <jwboyer@gmail.com>]

On Fri, 22 Feb 2008 22:15:58 +0300
Valentine Barshak <vbarshak@ru.mvista.com> wrote:

> Benjamin Herrenschmidt wrote:
> > On Thu, 2008-02-21 at 17:46 +0300, Valentine Barshak wrote:
> >> The PowerPC 440GX Taishan board fails to reset EMAC3 (reset timeout error)
> >> and because of that it can't find PHY chip. The older ibm_emac driver had
> >> a workaround for that: the EMAC_CLK_INTERNAL/EMAC_CLK_EXTERNAL macros which
> >> toggle the Ethernet Clock Select bit in the SDR0_MFR register. This patch
> >> does the same for "ibm,emac-440gx" compatible chips.
> > 
> > The main problem is that will force clock on -all- EMACs ... which can
> > be a problem as they can be in probe at the same time. Might be worth
> > also adding a global mutex around that block.
> 
> I've tried to move clock selection inside the global emac_phy_map_lock 
> block. That works fine for 440GX.
> 
> > 
> > Also, would you mind having a look at the other workaround for the
> > similar bug?
> 
> OK, I'll add 440EP/440GR workaround, but I'm not sure if we need it for
> the currently supported boards. The older ibm_emac driver also has a 
> workaround for it on 405ep. This part uses CPC0 dcr registers. So, looks 
> like we'll have to search device tree for the CPC0 entry in ibm_newemac 
> driver, map dcr registers and select clock with dcr_read/write calls. 
> I've omitted the 405ep part, since there's currently no board supported.

I'll be doing a 405EP port for .26.

josh