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. 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
