eMMC tuning issue on Odroid C2 and a possible solution

[jbrunet@baylibre.com (Jerome Brunet)]

On Thu, 2017-10-12 at 21:49 +0200, Heiner Kallweit wrote:
> > The result of the tuning does not depends on starting point, so I don't
> > really
> > understand how it would significantly change things.
> > 
> 
> I think it depends on the tx phase starting point.
> 

If the result of the tuning is not independent of the starting, instead of just
telling me, it is fairly easy for you to give actual result, like I asked you:

> > Ok, starting from Rx:0 Tx:270 then tuning gives you Tx:300 Rx:90
> > And what different did it gives you starting Rx:0/Tx:0 ?

And if the result are indeed vastly different, let's debug and get a real
explanation.

> Tuning does:
> rx phase tuning
> tx phase tuning
> rx phase tuning
> 
> Result of each step depends on result of previous step.

Again, we don't agree. 

> So also the initial
> rx phase tuning result depends on the starting point of tx phase.

The first Rx tuning is there only to get a sane starting point for the tx tuning
,as explained in the code. This is the reason why is not done when re-tuning.