Re: Initial signal voltage ?

[Joakim Tjernlund <joakim.tjernlund@transmode.se>]

On Tue, 2015-08-25 at 14:05 +0200, Ulf Hansson wrote:
> On 10 August 2015 at 18:50, Joakim Tjernlund
> <joakim.tjernlund@transmode.se> wrote:
> > in mmc_power_up() we have:
> >         /* Try to set signal voltage to 3.3V but fall back to 1.8v or 1.2v */
> >         if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330) == 0)
> >                 dev_err(mmc_dev(host), "Initial signal voltage of 3.3v\n");
> >         else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180) == 0)
> >                 dev_err(mmc_dev(host), "Initial signal voltage of 1.8v\n");
> >         else if (__mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_120) == 0)
> >                 dev_err(mmc_dev(host), "Initial signal voltage of 1.2v\n");
> > 
> > Here one jut brutally tries to set the initial power to 3.3 but nowhere in
> > general code there is a check if the controller can handle this w.r.t
> > HOST CAPS.
> 
> You are right, it's brutal. :-)
> 
> Perhaps the host driver should return -EINVAL when a voltage level
> can't be reached. The above code should not print messages as errors,
> at least as long some voltage level can be used.
> 
> > Where should this check be performed, I am guessing either here or in sdhci?
> > This is all new to me so I am just throwing this out there
> 
> Do you want to send a patch?

No, you didn't answer the question