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Date: Mon, 25 Jul 2016 11:26:32 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Baolin Wang <baolin.wang@...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 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.
Kind regards
Uffe
> ---
> 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
>
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