Subject: Re: Atheros 8035 PHY only works when at803x_config_init() is commented out

From: Florian Fainelli <[email-masked]>
Date: Thu, 09 Apr 2015 10:25:28 -0700

On 09/04/15 08:22, Mason wrote:
> Mason wrote:
> 
>> Daniel Mack wrote:
>>
>>> My suggestion is to dump the entire register set when
>>> at803x_config_init() is entered and again when it's left. Then try to
>>> find the differences and see if you can bring the PHY into the needed
>>> mode through the existing configuration hooks in the kernel.
>>
>> [    0.685330] IDX= 1 796d != 7949
>> [    0.688490] IDX= 5 c1e1 != 0000
>> [    0.691647] IDX= 6 000f != 0004
>> [    0.694803] IDX=10 3800 != 0000
>> [    0.697960] IDX=17 bc10 != 0012
>> [    0.701115] IDX=19 7400 != 0000
>> [    0.704271] IDX=27 060e != 0600
>>
>> Hmmm, didn't expect so many differences. I'll have to take a closer look.
> 
> For the record, I dumped the PHY registers
> A) upon entering phy_init_hw
> B) before leaving phy_init_hw (thus right after at803x_config_init)
> 
> IDX 1: b2 LINK STATUS, b5 AUTO-NEGOTIATION COMPLETE
> => Difference in status bits, seems reasonable
> 
> IDX 5: Link partner ability (base page)
> => seems reasonable (no partner yet?)
> 
> IDX 6: Auto-Negotiation Expansion
> => seems reasonable (no partner yet?)
> 
> IDX 10: 1000 BASE-T Status (HW reset = SW reset = 0)
> (ALSO: Contents of this register clear after a read operation has
> occurred.)
> => Looks like my own read cleared it
> 
> IDX 17: PHY-Specific Status
> b1 = "POLARITY (real time)"?
> => Difference in status bits, seems reasonable? (
> 
> IDX 19: Interrupt Status
> => Looks like some interrupt requests might have been discarded?
> 
> IDX 27: This register is undocumented
> 
> Nothing looks suspicious, except maybe the Interrupt Status?
> 
> Is speed auto-negotiation supposed to be complete when phy_init_hw exits?

There is no such guarantee, and the PHY state machine is started later,
which will take care of auto-neg and other things.
-- 
Florian