Hi Marek, > When using CMD6 to switch eMMC card timing from HS200/HS400 to > HS/legacy, do not poll for the completion status using CMD13, but > rather wait 50mS.
Nit: mS -> ms
>
> Once the card receives the CMD6 and starts executing it, the bus is in
> undefined state until both the card finishes executing the command and
> until the controller switches the bus to matching timing
> configuration. During this time, it is not possible to transport any
> commands or data across the bus, which includes the CMD13.
Just out of curiosity - is this 50ms time written in some spec? Or is
it only specific to Renesas HS200/HS400 ?
>
> Signed-off-by: Marek Vasut <marek.vasut+rene...@gmail.com>
> Cc: Jaehoon Chung <jh80.ch...@samsung.com>
> ---
> NOTE: Linux does the same thing.
> ---
> drivers/mmc/mmc.c | 28 ++++++++++++++++++++--------
> 1 file changed, 20 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index c7730c9233..ababacf65a 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -720,7 +720,8 @@ static int mmc_send_ext_csd(struct mmc *mmc, u8
> *ext_csd) return err;
> }
>
> -int mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value)
> +static int __mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value,
> + bool send_status)
> {
> struct mmc_cmd cmd;
> int timeout = 1000;
> @@ -736,19 +737,29 @@ int mmc_switch(struct mmc *mmc, u8 set, u8
> index, u8 value) while (retries > 0) {
> ret = mmc_send_cmd(mmc, &cmd, NULL);
>
> - /* Waiting for the ready status */
> - if (!ret) {
> - ret = mmc_send_status(mmc, timeout);
> - return ret;
> + if (ret) {
> + retries--;
> + continue;
> + }
> +
> + if (!send_status) {
> + mdelay(50);
> + return 0;
> }
>
> - retries--;
> + /* Waiting for the ready status */
> + return mmc_send_status(mmc, timeout);
> }
>
> return ret;
>
> }
>
> +int mmc_switch(struct mmc *mmc, u8 set, u8 index, u8 value)
> +{
> + return __mmc_switch(mmc, set, index, value, true);
> +}
> +
> #if !CONFIG_IS_ENABLED(MMC_TINY)
> static int mmc_set_card_speed(struct mmc *mmc, enum bus_mode mode,
> bool hsdowngrade)
> @@ -780,8 +791,9 @@ static int mmc_set_card_speed(struct mmc *mmc,
> enum bus_mode mode, default:
> return -EINVAL;
> }
> - err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
> EXT_CSD_HS_TIMING,
> - speed_bits);
> +
> + err = __mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
> EXT_CSD_HS_TIMING,
> + speed_bits, !hsdowngrade);
> if (err)
> return err;
>
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lu...@denx.de
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