On 16/11/16 12:51, Ulf Hansson wrote:
> In cases when the mmc host doesn't support HW busy detection, polling for
> busy by using CMD13 is beneficial. The reasons have already been explained
> in earlier change logs.
>
> Moreover, when polling with CMD13 during bus timing changes, we should
> retry instead of fail when we get CRC errors.
>
> Switching from HS200 to HS400 and reverse includes several steps, where
> each step changes the bus speed timing. Let's improve the behaviour during
> these sequences, by allowing CMD13 polling for each of the step. Let's also
> make sure the CMD13 polling becomes retried, while receiving a CRC error.
I don't know we need to try to get polling for HS400. The support of HS400
suggests a relatively sophisticated host controller which really should
support busy waiting as well.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---
> drivers/mmc/core/mmc.c | 87 +++++++++++++++-----------------------------------
> 1 file changed, 26 insertions(+), 61 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 0b26383..24b9e72 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1094,8 +1094,7 @@ static int mmc_select_hs_ddr(struct mmc_card *card)
> static int mmc_select_hs400(struct mmc_card *card)
> {
> struct mmc_host *host = card->host;
> - unsigned int max_dtr;
> - int err = 0;
> + int err;
> u8 val;
>
> /*
> @@ -1105,34 +1104,26 @@ static int mmc_select_hs400(struct mmc_card *card)
> host->ios.bus_width == MMC_BUS_WIDTH_8))
> return 0;
>
> - /* Switch card to HS mode */
> - val = EXT_CSD_TIMING_HS;
> - err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> - EXT_CSD_HS_TIMING, val,
> - card->ext_csd.generic_cmd6_time, 0,
> - true, false, true);
> + /*
> + * Switch card to HS mode.
> + * First reduce to the HS frequency as CMD13 are sent to poll for busy
> + * and/or to validate the switch status.
> + */
> + mmc_set_clock(host, card->ext_csd.hs_max_dtr);
That was moved by commit 649c6059d2371fef886a8f967e21416204723d63
("mmc: mmc: Fix HS switch failure in mmc_select_hs400()") i.e. if you put it
back I would expect the gru board problem to reappear.
> + err = mmc_select_hs(card);
> if (err) {
> pr_err("%s: switch to high-speed from hs200 failed, err:%d\n",
> mmc_hostname(host), err);
> return err;
> }
>
> - /* Set host controller to HS timing */
> - mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
> -
> - /* Reduce frequency to HS frequency */
> - max_dtr = card->ext_csd.hs_max_dtr;
> - mmc_set_clock(host, max_dtr);
> -
> - err = mmc_switch_status(card);
> - if (err)
> - goto out_err;
> -
> - /* Switch card to DDR */
> - err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> - EXT_CSD_BUS_WIDTH,
> - EXT_CSD_DDR_BUS_WIDTH_8,
> - card->ext_csd.generic_cmd6_time);
> + /* Switch card to HS DDR */
> + err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> + EXT_CSD_BUS_WIDTH,
> + EXT_CSD_DDR_BUS_WIDTH_8,
> + card->ext_csd.generic_cmd6_time,
> + MMC_TIMING_MMC_DDR52,
> + true, true, true);
> if (err) {
> pr_err("%s: switch to bus width for hs400 failed, err:%d\n",
> mmc_hostname(host), err);
> @@ -1144,28 +1135,17 @@ static int mmc_select_hs400(struct mmc_card *card)
> card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> EXT_CSD_HS_TIMING, val,
> - card->ext_csd.generic_cmd6_time, 0,
> - true, false, true);
> + card->ext_csd.generic_cmd6_time,
> + MMC_TIMING_MMC_HS400,
> + true, true, true);
This is not exactly right. Tuning has been done at the HS400 operating
frequency. That is why we set the bus speed before sending any more
commands. i.e. mmc_switch_status(card) is below mmc_set_bus_speed(card)
> if (err) {
> pr_err("%s: switch to hs400 failed, err:%d\n",
> mmc_hostname(host), err);
> return err;
> }
>
> - /* Set host controller to HS400 timing and frequency */
> - mmc_set_timing(host, MMC_TIMING_MMC_HS400);
> mmc_set_bus_speed(card);
> -
> - err = mmc_switch_status(card);
> - if (err)
> - goto out_err;
> -
> return 0;
> -
> -out_err:
> - pr_err("%s: %s failed, error %d\n", mmc_hostname(card->host),
> - __func__, err);
> - return err;
> }
>
> int mmc_hs200_to_hs400(struct mmc_card *card)
> @@ -1187,27 +1167,17 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
> /* Switch HS400 to HS DDR */
> val = EXT_CSD_TIMING_HS;
> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING,
> - val, card->ext_csd.generic_cmd6_time, 0,
> - true, false, true);
> - if (err)
> - goto out_err;
> -
> - mmc_set_timing(host, MMC_TIMING_MMC_DDR52);
> -
> - err = mmc_switch_status(card);
> + val, card->ext_csd.generic_cmd6_time,
> + MMC_TIMING_MMC_DDR52,
> + true, true, true);
> if (err)
> goto out_err;
>
> /* Switch HS DDR to HS */
> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_BUS_WIDTH,
> EXT_CSD_BUS_WIDTH_8, card->ext_csd.generic_cmd6_time,
> - 0, true, false, true);
> - if (err)
> - goto out_err;
> -
> - mmc_set_timing(host, MMC_TIMING_MMC_HS);
> -
> - err = mmc_switch_status(card);
> + MMC_TIMING_MMC_HS,
> + true, true, true);
> if (err)
> goto out_err;
>
> @@ -1215,14 +1185,9 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
> val = EXT_CSD_TIMING_HS200 |
> card->drive_strength << EXT_CSD_DRV_STR_SHIFT;
> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING,
> - val, card->ext_csd.generic_cmd6_time, 0,
> - true, false, true);
> - if (err)
> - goto out_err;
> -
> - mmc_set_timing(host, MMC_TIMING_MMC_HS200);
> -
> - err = mmc_switch_status(card);
> + val, card->ext_csd.generic_cmd6_time,
> + MMC_TIMING_MMC_HS200,
> + true, true, true);
> if (err)
> goto out_err;
>
>
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