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mmc: Split device init to decouple OCR-polling delay

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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@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>
master
Che-Liang Chiou 12 years ago committed by Andy Fleming
parent 5ed6f447af
commit e95504497e
2 changed files with 135 additions and 32 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 137
      drivers/mmc/mmc.c
  2. 30
      include/mmc.h

137
drivers/mmc/mmc.c
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@ -524,48 +524,70 @@ 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;
@ -1274,7 +1296,7 @@ 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;
@ -1314,17 +1336,48 @@ 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;
}
@ -1362,6 +1415,25 @@ 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);
@ -1372,5 +1444,6 @@ int mmc_initialize(bd_t *bis)
print_mmc_devices(',');
do_preinit();
return 0;
}

30
include/mmc.h
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@ -68,6 +68,7 @@
#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
@ -270,6 +271,10 @@ struct mmc {
int (*getcd)(struct mmc *mmc);
int (*getwp)(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);
@ -287,6 +292,31 @@ int mmc_getcd(struct mmc *mmc);
int mmc_getwp(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);

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