[PATCH 1/6] mmc: sdhci: add platfrom get_max_timeout hook

[Shawn Guo]

On Wed, Dec 11, 2013 at 11:00:03AM +0800, Dong Aisheng wrote:
> >> @@ -2930,7 +2930,10 @@ int sdhci_add_host(struct sdhci_host *host)
> >>       if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
> >>               host->timeout_clk = mmc->f_max / 1000;
> >>
> >> -     mmc->max_discard_to = (1 << 27) / host->timeout_clk;
> >> +     if (host->ops->get_max_timeout)
> >> +             mmc->max_discard_to = host->ops->get_max_timeout(host);
> >
> > Does "timeout" conceptually equals to "discard_to"?  If not, we might
> > want to write it in the either form below to avoid messing these two
> > concepts.
> >
> 
> No, they're two concepts but the max_discard_to equals to the max timeout value
> the host supports.

Does it?  Shouldn't max_discard_to equals to max_timeout_value / timeout_clk?

> 
> >         mmc->max_discard_to = host->ops->get_max_timeout(host) / host->timeout_clk;
> >
> > or
> >
> >         mmc->max_discard_to = host->ops->get_max_discard_to(host);
> >
> > I guess you may want to go for the second one.
> >
> 
> The original way looks ok to me.
> Platform host driver does not need to know detail about discard,
> just tell the max timeout value it supports is ok.
> Common sdhci driver will handle it well.

Well, looking at the patch #2, esdhc_get_max_timeout() returns

  max_to / (esdhc_pltfm_get_max_clock(host) / 1000)

not just the max timeout value - max_to, so your platform host driver
is knowing and handling the details about discard_ro, i.e. the
discard_ro has to be max_timeout_value / timeout_clk.

Shawn