[U-Boot] [PATCH v2] mmc: Split device init to decouple OCR-polling delay
Jae hoon Chung
jh80.chung at gmail.com
Thu Nov 29 16:20:01 CET 2012
Hi Simon,
Is it saved the 200ms? Could you tell me your environment?
I will check this patch..and share the result.
Best Regards,
Jaehoon Chung
2012/11/29 Simon Glass <sjg at chromium.org>:
> From: Che-Liang Chiou <clchiou at chromium.org>
>
> Most of time that MMC driver spends on initializing a device is polling
> OCR (operation conditions register). To decouple this polling loop,
> device init is split into two parts: The first part fires the OCR query
> command, and the second part polls the result. So the caller is now no
> longer bound to the OCR-polling delay; he may fire the query, go
> somewhere and then come back later for the result.
>
> To use this, call mmc_set_preinit() on any device which needs this.
>
> This can save significant amounts of time on boot (e.g. 200ms) by
> hiding the MMC init time behind other init.
>
> Signed-off-by: Che-Liang Chiou <clchiou at chromium.org>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
> Changes in v2:
> - Rebase to master
>
> drivers/mmc/mmc.c | 137 ++++++++++++++++++++++++++++++++++++++++------------
> include/mmc.h | 30 ++++++++++++
> 2 files changed, 135 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index 72e8ce6..09695e8 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -503,48 +503,70 @@ static int sd_send_op_cond(struct mmc *mmc)
> return 0;
> }
>
> -static int mmc_send_op_cond(struct mmc *mmc)
> +/* We pass in the cmd since otherwise the init seems to fail */
> +static int mmc_send_op_cond_iter(struct mmc *mmc, struct mmc_cmd *cmd,
> + int use_arg)
> {
> - int timeout = 10000;
> - struct mmc_cmd cmd;
> int err;
>
> + cmd->cmdidx = MMC_CMD_SEND_OP_COND;
> + cmd->resp_type = MMC_RSP_R3;
> + cmd->cmdarg = 0;
> + if (use_arg && !mmc_host_is_spi(mmc)) {
> + cmd->cmdarg =
> + (mmc->voltages &
> + (mmc->op_cond_response & OCR_VOLTAGE_MASK)) |
> + (mmc->op_cond_response & OCR_ACCESS_MODE);
> +
> + if (mmc->host_caps & MMC_MODE_HC)
> + cmd->cmdarg |= OCR_HCS;
> + }
> + err = mmc_send_cmd(mmc, cmd, NULL);
> + if (err)
> + return err;
> + mmc->op_cond_response = cmd->response[0];
> + return 0;
> +}
> +
> +int mmc_send_op_cond(struct mmc *mmc)
> +{
> + struct mmc_cmd cmd;
> + int err, i;
> +
> /* Some cards seem to need this */
> mmc_go_idle(mmc);
>
> /* Asking to the card its capabilities */
> - cmd.cmdidx = MMC_CMD_SEND_OP_COND;
> - cmd.resp_type = MMC_RSP_R3;
> - cmd.cmdarg = 0;
> -
> - err = mmc_send_cmd(mmc, &cmd, NULL);
> + mmc->op_cond_pending = 1;
> + for (i = 0; i < 2; i++) {
> + err = mmc_send_op_cond_iter(mmc, &cmd, i != 0);
> + if (err)
> + return err;
>
> - if (err)
> - return err;
> + /* exit if not busy (flag seems to be inverted) */
> + if (mmc->op_cond_response & OCR_BUSY)
> + return 0;
> + }
> + return IN_PROGRESS;
> +}
>
> - udelay(1000);
> +int mmc_complete_op_cond(struct mmc *mmc)
> +{
> + struct mmc_cmd cmd;
> + int timeout = 1000;
> + uint start;
> + int err;
>
> + mmc->op_cond_pending = 0;
> + start = get_timer(0);
> do {
> - cmd.cmdidx = MMC_CMD_SEND_OP_COND;
> - cmd.resp_type = MMC_RSP_R3;
> - cmd.cmdarg = (mmc_host_is_spi(mmc) ? 0 :
> - (mmc->voltages &
> - (cmd.response[0] & OCR_VOLTAGE_MASK)) |
> - (cmd.response[0] & OCR_ACCESS_MODE));
> -
> - if (mmc->host_caps & MMC_MODE_HC)
> - cmd.cmdarg |= OCR_HCS;
> -
> - err = mmc_send_cmd(mmc, &cmd, NULL);
> -
> + err = mmc_send_op_cond_iter(mmc, &cmd, 1);
> if (err)
> return err;
> -
> - udelay(1000);
> - } while (!(cmd.response[0] & OCR_BUSY) && timeout--);
> -
> - if (timeout <= 0)
> - return UNUSABLE_ERR;
> + if (get_timer(start) > timeout)
> + return UNUSABLE_ERR;
> + udelay(100);
> + } while (!(mmc->op_cond_response & OCR_BUSY));
>
> if (mmc_host_is_spi(mmc)) { /* read OCR for spi */
> cmd.cmdidx = MMC_CMD_SPI_READ_OCR;
> @@ -1227,7 +1249,7 @@ block_dev_desc_t *mmc_get_dev(int dev)
> }
> #endif
>
> -int mmc_init(struct mmc *mmc)
> +int mmc_start_init(struct mmc *mmc)
> {
> int err;
>
> @@ -1267,17 +1289,48 @@ int mmc_init(struct mmc *mmc)
> if (err == TIMEOUT) {
> err = mmc_send_op_cond(mmc);
>
> - if (err) {
> + if (err && err != IN_PROGRESS) {
> printf("Card did not respond to voltage select!\n");
> return UNUSABLE_ERR;
> }
> }
>
> - err = mmc_startup(mmc);
> + if (err == IN_PROGRESS)
> + mmc->init_in_progress = 1;
> +
> + return err;
> +}
> +
> +static int mmc_complete_init(struct mmc *mmc)
> +{
> + int err = 0;
> +
> + if (mmc->op_cond_pending)
> + err = mmc_complete_op_cond(mmc);
> +
> + if (!err)
> + err = mmc_startup(mmc);
> if (err)
> mmc->has_init = 0;
> else
> mmc->has_init = 1;
> + mmc->init_in_progress = 0;
> + return err;
> +}
> +
> +int mmc_init(struct mmc *mmc)
> +{
> + int err = IN_PROGRESS;
> + unsigned start = get_timer(0);
> +
> + if (mmc->has_init)
> + return 0;
> + if (!mmc->init_in_progress)
> + err = mmc_start_init(mmc);
> +
> + if (!err || err == IN_PROGRESS)
> + err = mmc_complete_init(mmc);
> + debug("%s: %d, time %lu\n", __func__, err, get_timer(start));
> return err;
> }
>
> @@ -1315,6 +1368,25 @@ int get_mmc_num(void)
> return cur_dev_num;
> }
>
> +void mmc_set_preinit(struct mmc *mmc, int preinit)
> +{
> + mmc->preinit = preinit;
> +}
> +
> +static void do_preinit(void)
> +{
> + struct mmc *m;
> + struct list_head *entry;
> +
> + list_for_each(entry, &mmc_devices) {
> + m = list_entry(entry, struct mmc, link);
> +
> + if (m->preinit)
> + mmc_start_init(m);
> + }
> +}
> +
> +
> int mmc_initialize(bd_t *bis)
> {
> INIT_LIST_HEAD (&mmc_devices);
> @@ -1325,5 +1397,6 @@ int mmc_initialize(bd_t *bis)
>
> print_mmc_devices(',');
>
> + do_preinit();
> return 0;
> }
> diff --git a/include/mmc.h b/include/mmc.h
> index a13e2bd..445d714 100644
> --- a/include/mmc.h
> +++ b/include/mmc.h
> @@ -62,6 +62,7 @@
> #define UNUSABLE_ERR -17 /* Unusable Card */
> #define COMM_ERR -18 /* Communications Error */
> #define TIMEOUT -19
> +#define IN_PROGRESS -20 /* operation is in progress */
>
> #define MMC_CMD_GO_IDLE_STATE 0
> #define MMC_CMD_SEND_OP_COND 1
> @@ -260,6 +261,10 @@ struct mmc {
> int (*init)(struct mmc *mmc);
> int (*getcd)(struct mmc *mmc);
> uint b_max;
> + char op_cond_pending; /* 1 if we are waiting on an op_cond command */
> + char init_in_progress; /* 1 if we have done mmc_start_init() */
> + char preinit; /* start init as early as possible */
> + uint op_cond_response; /* the response byte from the last op_cond */
> };
>
> int mmc_register(struct mmc *mmc);
> @@ -276,6 +281,31 @@ int mmc_switch_part(int dev_num, unsigned int part_num);
> int mmc_getcd(struct mmc *mmc);
> void spl_mmc_load(void) __noreturn;
>
> +/**
> + * Start device initialization and return immediately; it does not block on
> + * polling OCR (operation condition register) status. Then you should call
> + * mmc_init, which would block on polling OCR status and complete the device
> + * initializatin.
> + *
> + * @param mmc Pointer to a MMC device struct
> + * @return 0 on success, IN_PROGRESS on waiting for OCR status, <0 on error.
> + */
> +int mmc_start_init(struct mmc *mmc);
> +
> +/**
> + * Set preinit flag of mmc device.
> + *
> + * This will cause the device to be pre-inited during mmc_initialize(),
> + * which may save boot time if the device is not accessed until later.
> + * Some eMMC devices take 200-300ms to init, but unfortunately they
> + * must be sent a series of commands to even get them to start preparing
> + * for operation.
> + *
> + * @param mmc Pointer to a MMC device struct
> + * @param preinit preinit flag value
> + */
> +void mmc_set_preinit(struct mmc *mmc, int preinit);
> +
> #ifdef CONFIG_GENERIC_MMC
> #define mmc_host_is_spi(mmc) ((mmc)->host_caps & MMC_MODE_SPI)
> struct mmc *mmc_spi_init(uint bus, uint cs, uint speed, uint mode);
> --
> 1.7.7.3
>
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
More information about the U-Boot
mailing list