On Tue, Aug 23, 2016 at 05:02:56PM +0200, Ulf Hansson wrote:
> [...]
>
> >> > +static int tmio_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
> >> > +{
> >> > + struct tmio_mmc_host *host = mmc_priv(mmc);
> >> > + unsigned int num;
> >> > + int i, ret = 0;
> >> > + bool *tap;
> >> > +
> >> > + if (!host->init_tuning || !host->select_tuning)
> >>
> >> When defining these callbacks, it would be nice to know which ones are
> >> optional and which ones are required.
> >
> > Would some comments in struct tmio_mmc_host be an appropriate way
> > to achieve that?
>
> Yes, that would be nice!
>
> [...]
>
> >> > static int tmio_mmc_init_ocr(struct tmio_mmc_host *host)
> >> > @@ -1202,6 +1276,9 @@ int tmio_mmc_host_runtime_suspend(struct device
> >> > *dev)
> >> > struct mmc_host *mmc = dev_get_drvdata(dev);
> >> > struct tmio_mmc_host *host = mmc_priv(mmc);
> >> >
> >> > + mmc_retune_timer_stop(host->mmc);
> >> > + mmc_retune_needed(host->mmc);
> >>
> >> I am wondering whether it would it be possible to keep a cache of the
> >> currently used tuning values and then restore these values at
> >> runtime_resume?
> >>
> >> In that way you wouldn't need to force new re-tuning cycle here.
> >
> > I will check with the hardware people to see if it is practical from
> > that POV.
>
> Okay!
The feedback I received is something like this:
* The tap values calculated during retuning depend on the temperature of
the SoC and card.
* So after resume the values may be invalid.
* It may be possible to re-use the TAP values and re-tune if a transfer
fails but the people I spoke with were unsure of the merit of that
approach
Personally my feeling is that we should initiate a retune on resume for
now as that seems to be the safest option.
> > From a software POV that ought to be simple enough: a small bitmap ought
> > to be sufficient to save the values for the hardware covered by this
> > series.
>
> Yes, indeed!
>
> Kind regards
> Uffe
>
