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Date: Mon, 25 Jul 2016 17:29:46 +0800
From: Baolin Wang <baolin.wang@...aro.org>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
Russell King <rmk+kernel@....linux.org.uk>,
Shawn Lin <shawn.lin@...k-chips.com>,
Doug Anderson <dianders@...omium.org>,
Heiko Stübner <heiko@...ech.de>,
David Jander <david@...tonic.nl>,
Hans de Goede <hdegoede@...hat.com>,
linux-mmc <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Mark Brown <broonie@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v3] mmc: Change the max discard sectors and erase response
if mmc host supports busy signalling
On 25 July 2016 at 17:26, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> On 25 July 2016 at 10:48, Baolin Wang <baolin.wang@...aro.org> 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.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
>
> Thanks, applied for next! I took the liberty to update the change-log
> a bit to clarify things!
>
> Thanks a lot for working on this long outstanding problem!
>
> In the next step I plan to remove the MMC_CAP_ERASE and instead enable
> it by default, although let's leave that for v4.9.
OK. I will investigate that and send patch to fix that. Thanks for
your useful suggetion.:)
>> ---
>> Changes since v2:
>> - Remove the 'MMC_CAP_WAIT_WHILE_BUSY' flag checking when deciding
>> if we can use R1B response.
>> - Avoid polling CMD13 when using R1B response.
>> - Use earlier calculated erase timeout as the polling time.
>>
>> Changes since v1:
>> - Remove the 'MMC_CAP_WAIT_WHILE_BUSY' flag checking when deciding
>> the max discard sectors.
>> ---
>> drivers/mmc/core/core.c | 60 +++++++++++++++++++++++++++++++++++++++--------
>> 1 file changed, 50 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 8b4dfd4..b4c08d1a 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -2060,7 +2060,8 @@ 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;
>> + bool use_r1b_resp = false;
>> unsigned long timeout;
>> int err;
>>
>> @@ -2128,8 +2129,22 @@ 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) {
>> + cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
>> + } else {
>> + cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
>> + cmd.busy_timeout = busy_timeout;
>> + use_r1b_resp = true;
>> + }
>> +
>> err = mmc_wait_for_cmd(card->host, &cmd, 0);
>> if (err) {
>> pr_err("mmc_erase: erase error %d, status %#x\n",
>> @@ -2141,7 +2156,14 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
>> if (mmc_host_is_spi(card->host))
>> goto out;
>>
>> - timeout = jiffies + msecs_to_jiffies(MMC_CORE_TIMEOUT_MS);
>> + /*
>> + * In case of when R1B + MMC_CAP_WAIT_WHILE_BUSY is used, the polling
>> + * shall be avoided.
>> + */
>> + if ((card->host->caps & MMC_CAP_WAIT_WHILE_BUSY) && use_r1b_resp)
>> + goto out;
>> +
>> + timeout = jiffies + msecs_to_jiffies(busy_timeout);
>> do {
>> memset(&cmd, 0, sizeof(struct mmc_command));
>> cmd.opcode = MMC_SEND_STATUS;
>> @@ -2321,23 +2343,41 @@ 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 */
>> + /*
>> + * 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 no
>> + * matter what size of 'host->max_busy_timeout', but if the
>> + * 'host->max_busy_timeout' is large enough for more discard sectors,
>> + * then we can continue to increase the max discard sectors until we
>> + * get a balance value.
>> + */
>> 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)
>> +
>> + if (qty + x > min_qty &&
>> + timeout > host->max_busy_timeout)
>> break;
>> +
>> if (timeout < last_timeout)
>> break;
>> last_timeout = timeout;
>> --
>> 1.7.9.5
>>
--
Baolin.wang
Best Regards
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