On Wed, Sep 03, 2014 at 09:32:35AM +0200, Ulf Hansson wrote: > On 3 September 2014 08:51, Dong Aisheng <dongas86@xxxxxxxxx> wrote: > > Hi Ulf, > > > > On Thu, Jan 30, 2014 at 6:37 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > >> This patchset improves the handling around busy detection in the mmc core layer > >> while operating on host supporting MMC_CAP_WAIT_WHILE_BUSY. > >> > >> A R1B response is for an mmc command, specified as and R1 but with an optional > >> busy assertion on the DAT0 line. Hosts supporting MMC_CAP_WAIT_WHILE_BUSY, > >> normally has a busy detection mechanism build in it's controller HW. > >> > >> Using such a feature decreases the need for polling of the card's status using > >> CMD13, which is the fallback method used by the mmc core for hosts that don't > >> support MMC_CAP_WAIT_WHILE_BUSY. > >> > >> Typcial commands that expects R1B responses are CMD6 (SWITCH), CMD12 (STOP), > >> CMD38 (ERASE) and CMD5 (SLEEP). This patchset adresses CMD6, CMD5 and improves > >> some parts where CMD12 are used. If the implemented approach becomes accepted, > >> a future patchset for CMD38 can be based on top if this patchset. > >> > >> Do note, the final two patches implements support for busy detection for the > >> mmci host driver, since some of it's HW variants do supports busy detection. > >> > >> Future suggested improvements related to this patchset: (Please, feel free to > >> implement any of them :-) ). > >> > >> a) For CMD38, select a fixed number maximum blocks to accept for > >> erase/discard/trim operations. Compute the needed timeout depending on each > >> card's erase information provided through it's CSD/EXT_CSD registers. Then > >> follow the same principle as for sending a CMD6. > >> > >> b) At least for CMD38, but likely for other commands as well, we could benefit > >> from doing a _periodic_ CMD13 polling to handle the busy completion. This will > >> also be useful for hosts supporting MMC_CAP_WAIT_WHILE_BUSY, in particular for > >> cases where the host are unable to support the needed busy timeout. > >> > > > > Do you have the plan to implement above two items? > > Yes, it's on top of my TODO list for MMC. I really need to get this > done asap. Thanks for pinging me about this. > Great! > > Since currently the max_discard_sectors is still calculated based on > > max_busy_timeout of host, > > it is possible that for some eMMC chips, the max_discard_sectors is 1, > > which then cause the erase operation terribly slow. > > Yes! > > Another issue to fix is get MMC_CAP_ERASE removed - and that should be > possible once the above described problem has been solved. > Yes, seems MMC_CAP_ERASE is not needed anymore. Regards Dong Aisheng > 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
