Hi, Ulf. On 09/03/2014 04:32 PM, 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. > >> 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. Did you send the patch V2 for this patch-set? Best Regards, Jaehoon Chung > > 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 > -- 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
