On Tue, 29 Sep 2009 23:10:13 -0700 Philip Langdale wrote: > On Tue, 29 Sep 2009 23:37:32 +0200 > Pierre Ossman wrote: > > > I must have missed that part of discussion. If the voltage fully > > overlaps with the MMC definition, then I don't see the controllers > > having to be designed explicitly for SD 3.0. If not, then we probably > > need a new voltage bit for the hosts. In that case separating > > supporting from non-supporting should sort itself out easily. > > The reason I think we need is a host cap is that low voltage operations > apparently implies different signal timings. This is second hand from > David as there are no public specs for 3.0 available yet. So, the > failure case is a controller that publishes support for low voltage, > but only expects MMC cards to use it. > > In practice, I expect that the timings are close enough that this will > work anyway, but I think the situation is analogous to HS-MMC vs HS-SD. > There the timings are slightly different and you felt it was enough to > justify a separate host cap for each one. > It's difficult to say without seeing the spec. But if things are not backwards compatible, then we should probably add either a new timing mode, or a new bus mode (where we have open drain and push pull today). > In fact, thinking about it in those terms, it suggests we need to > retroactively introduce a reduced-voltage MMC host flag too, just in > case SDHCI 3.0 controllers barf on those cards... > Maybe. Again, it's difficult to say without seeing the specifics of the new specification. Rgds -- -- Pierre Ossman WARNING: This correspondence is being monitored by the Swedish government. Make sure your server uses encryption for SMTP traffic and consider using PGP for end-to-end encryption.