On 2 April 2015 at 12:30, Arend van Spriel <arend@xxxxxxxxxxxx> wrote: > On 04/02/15 10:43, Ulf Hansson wrote: >> >> [...] >>>>>> >>>>>> - ability to hold off re-tuning if the card is busy >>>>> >>>>> >>>>> >>>>> What do you mean by "card is busy"? >>>> >>>> >>>> >>>> I guess, more accurately, any time the card is in a state that is >>>> incapable >>>> of supporting re-tuning. For example: >>>> - DAT0 busy >>> >>> >>> >>> This state is not specific to re-tuning. An SDIO device can keep DAT0 >>> busy >>> at which the host controller can not start another request. >> >> >> Not entirely true. Some commands are allowed during this period, for >> example CMD13 (which doesn't exist for SDIO) > > > Yeah. I was wondering whether to mention that. > >> Anyway, I get the point. Thanks! >> >>> >>>> - between dependent commands like erase start, end, etc >>>> - card is asleep >>>> Also SDIO cards can have a custom sleep state where tuning won't work. >>> >>> >>> >>> Our SDIO wifi device has such a state and it can only come out of it upon >>> CMD52 write or CMD14 (ExitSleep). >> >> >> So how will the mmc core know about these states? I guess we will >> require SDIO func drivers to deal with enable/disable or hold/release >> of re-tuning then? > > > This is actually why in the past we tried to only kick off retuning before a > request that requires use of data line(s) so mmc core (or sdhci) would not > do re-tuning when SDIO func used CMD52 to wakeup the device. I never tried > CMD14 approach and not even sure from which spec it comes (maybe eMMC). That's an interesting idea. It would eliminate the need for SDIO func drivers to care about holding/releasing re-tuning. Would be nice to hear about Adrian's thoughts around this as well. > >> I don't like this, but if there is no other way... Also, we must be >> very careful on which API we exports for SDIO func drivers to use. The >> can easily be misinterpreted. >> >> [...] Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
