Re: [RESEND RFC v2] mmc: Change the max discard sectors and erase response if mmc host supports busy signalling

[Ulf Hansson]

On 18 July 2016 at 13:17, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
> Hi Ulf,
>
> On 28 June 2016 at 15:25, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote:
>> When mmc host HW supports busy signalling (using R1B as response), We
>> shouldn't use 'host->max_busy_timeout' as the limitation when deciding
>> the max discard sectors that we tell the generic BLOCK layer about.
>> Instead, we should pick one preferred erase size as the max discard
>> sectors.
>>
>> If the host controller supports busy signalling and the timeout for
>> the erase operation does not exceed the max_busy_timeout, we should
>> use R1B response. Or we need to prevent the host from doing hw busy
>> detection, which is done by converting to a R1 response instead.
>>
>> Changes since v1:
>>   - Remove the 'MMC_CAP_WAIT_WHILE_BUSY' flag checking when deciding
>>     the max discard sectors.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
>> ---
>>  drivers/mmc/core/core.c |   47 +++++++++++++++++++++++++++++++++++++++--------
>>  1 file changed, 39 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 8b4dfd4..edd43b1 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -2060,7 +2060,7 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
>>                         unsigned int to, unsigned int arg)
>>  {
>>         struct mmc_command cmd = {0};
>> -       unsigned int qty = 0;
>> +       unsigned int qty = 0, busy_timeout = 0;
>>         unsigned long timeout;
>>         int err;
>>
>> @@ -2128,8 +2128,23 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
>>         memset(&cmd, 0, sizeof(struct mmc_command));
>>         cmd.opcode = MMC_ERASE;
>>         cmd.arg = arg;
>> -       cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
>> -       cmd.busy_timeout = mmc_erase_timeout(card, arg, qty);
>> +       busy_timeout = mmc_erase_timeout(card, arg, qty);
>> +       /*
>> +        * If the host controller supports busy signalling and the timeout for
>> +        * the erase operation does not exceed the max_busy_timeout, we should
>> +        * use R1B response. Or we need to prevent the host from doing hw busy
>> +        * detection, which is done by converting to a R1 response instead.
>> +        */
>> +       if ((card->host->max_busy_timeout &&
>> +           busy_timeout > card->host->max_busy_timeout) ||
>> +           !(card->host->caps & MMC_CAP_WAIT_WHILE_BUSY)) {
>> +               cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
>> +               cmd.busy_timeout = 0;
>> +       } else {
>> +               cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
>> +               cmd.busy_timeout = busy_timeout;
>> +       }
>> +
>>         err = mmc_wait_for_cmd(card->host, &cmd, 0);
>>         if (err) {
>>                 pr_err("mmc_erase: erase error %d, status %#x\n",
>> @@ -2321,23 +2336,39 @@ static unsigned int mmc_do_calc_max_discard(struct mmc_card *card,
>>                                             unsigned int arg)
>>  {
>>         struct mmc_host *host = card->host;
>> -       unsigned int max_discard, x, y, qty = 0, max_qty, timeout;
>> +       unsigned int max_discard, x, y, qty = 0, max_qty, min_qty, timeout;
>>         unsigned int last_timeout = 0;
>>
>> -       if (card->erase_shift)
>> +       if (card->erase_shift) {
>>                 max_qty = UINT_MAX >> card->erase_shift;
>> -       else if (mmc_card_sd(card))
>> +               min_qty = card->pref_erase >> card->erase_shift;
>> +       } else if (mmc_card_sd(card)) {
>>                 max_qty = UINT_MAX;
>> -       else
>> +               min_qty = card->pref_erase;
>> +       } else {
>>                 max_qty = UINT_MAX / card->erase_size;
>> +               min_qty = card->pref_erase / card->erase_size;
>> +       }
>>
>>         /* Find the largest qty with an OK timeout */
>>         do {
>>                 y = 0;
>>                 for (x = 1; x && x <= max_qty && max_qty - x >= qty; x <<= 1) {
>>                         timeout = mmc_erase_timeout(card, arg, qty + x);
>> -                       if (timeout > host->max_busy_timeout)
>> +                       /*
>> +                        * We should not only use 'host->max_busy_timeout' as
>> +                        * the limitation when deciding the max discard sectors.
>> +                        * We should set a balance value to improve the erase
>> +                        * speed, and it can not get too long timeout at the
>> +                        * same time.
>> +                        *
>> +                        * Here we set 'card->pref_erase' as the minimal discard
>> +                        * sectors when deciding the max discard sectors.
>> +                        */
>> +                       if (qty + x > min_qty &&
>> +                           timeout > host->max_busy_timeout)
>>                                 break;
>> +
>>                         if (timeout < last_timeout)
>>                                 break;
>>                         last_timeout = timeout;
>> --
>> 1.7.9.5
>>
>
> Do you have any comments about this patch? Thanks.

Sorry for the delay.

I will have a look asap!

Kind regards
Uffe