On 5 May 2014 18:55, Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx> wrote:
> I got a Micron eMMC 4.41 memory and I am trying to use the TRIM function.
> my EXT_CSD_TRIM_MULT is 15 which gets me a tmo of 15*300=4500 ms
> Then in mmc_calc_max_discard() I have:
> max_discard = mmc_do_calc_max_discard(card, MMC_ERASE_ARG);
> if (mmc_can_trim(card)) {
> max_trim = mmc_do_calc_max_discard(card, MMC_TRIM_ARG);
> if (max_trim < max_discard)
> max_discard = max_trim;
> } else if (max_discard < card->erase_size) {
> max_discard = 0;
> }
> pr_debug("%s: calculated max. discard sectors %u for timeout %u
> ms\n",
> mmc_hostname(host), max_discard, host->max_busy_timeout);
> Now mmc_do_calc_max_discard(card, MMC_TRIM_ARG) returns 0 because the
> initial trim
> timeout is so high, 4500 ms:
> mmc0: calculated max. discard sectors 0 for timeout 2684 ms
>
> How is this supposed to work?
This piece of code in the mmc core/block layer is somewhat broken :-(
For 3.15 we merged quite some patches to fixup the hardware busy
detection mechanism supported by some host drivers/controllers.
Trim/erase may utilize hardware busy detections, it's therefore I
gives you this background.
Now, those fixes did not mean any improvements immediately for
erase/trim, but made some preparations for us to fix it. :-) I have it
on the top of my mmc-TODO list - that's all I can give you sorry. :-)
Anyway, what host driver / controller are you using?
Kind regards
Ulf Hansson
>
> Jocke
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