On 12/17/2013 08:32 PM, Dong Aisheng wrote: > On Wed, Dec 18, 2013 at 1:27 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: >> On 12/17/2013 02:25 AM, Dong Aisheng wrote: >>> Hi Stephen, >>> >>> On Sat, Dec 14, 2013 at 6:43 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: >>>> On one of my eMMC devices, I see the following results from calling >>>> mmc_do_calc_max_discard() with various parameters: >>>> >>>> [ 3.057263] MMC_DISCARD_ARG max_discard 1 >>>> [ 3.057266] MMC_ERASE_ARG max_discard 4096 >>>> [ 3.057267] MMC_TRIM_ARG max_discard 1 >>>> >>>> This causes mmc_calc_max_discard() to return 1, which makes the discard >>>> IOCTL extremely slow. >>>> >>> >>> IMX met the similar issue. >>> http://www.spinics.net/lists/linux-mmc/msg23375.html >>> It's caused by the max_discard_to supported by host is too small. >>> >>> I submitted the fix patches: >>> http://www.spinics.net/lists/arm-kernel/msg294924.html >>> Please see if it helps for you, especially patch #5. >>> It could increase the max_discard_to if Tegra has same problem. >> ... >> Even on the boards where your patch solves the problem, isn't it just a >> temporary measure; as soon as we upstream the changes to enable the >> faster transfer modes, we'll have a faster SDCLK, and hence again be >> limited in the discard size, perhaps down to a single sector again. > > Actually my patch is intend to fix 1) IMX incorrect max timeout issue > 2) should not use max_clock > to calculate max_discard_to issue for using SDCLK as timeout clock. > The issue discussed here is a different issue that the card timeout > may still be bigger than > the host capability and how to use discard for such case. > So your problem may exist if you meet some more big timeout cards. > For IMX, when running at 50Mhz, the max timeout is more than 5s. > It looks bigger enough currently and i tested many eMMC cards(Samsung, > Toshiba, Sandisk, Hynix) > and all they worked well with discard after fix. > I don't know which eMMC cards you meet the issue and don't know what > is Tegra max timeout. > Just for SD3.0 cards working on 200Mhz, i observed one Toshiba > SDHC U1 card could not do discard, since its AU erase timeout is 2s+ > which exceeds the host > capability 1335ms. Thus discard is automatically disabled. > But another Sandisk SDXC can still work well since it has small > ERASE_OFFSET as 1s. On the more recent Tegra boards, the eMMC devices appear to have an erase timeout of 4200ms for a single erase block! That's more than the ~2600ms max controller timeout at 48MHz on Tegra:-( (that is unless Tegra also supports more than 27 bits of timeout register) -- 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
