Hi,
This concept is very good. But I have one question. I think need to call mmc_init() one more, right? how did you save the boot time(200ms)?
On 11/29/2012 10:21 AM, Simon Glass wrote:
From: Che-Liang Chiou clchiou@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.
snip..
+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);
It need not to return? if err is IN_PROGRESS, next condition is immediately run. Then i think we didn't save the time before adjust this patch.
- 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);