imx6q eMMC Fast Boot, someone using it can help ?

[angelo_d]

Dear all,

i re-open a thread from a previous post, that was at a certain point not discussed anymore for missing of information.

I read that eMMC "Fast Boot" should fast-up a bit the eMMC boot process, at least this seems to be confirmed from the

boot flow charts. Not sure it can be useful in my case, where i just boot a 250KB u-boot, but if it can improve the boot time, even few

milliseconds, it can be good for me.

Here my updated situation:

- If i try to enable Fast Boot option, with or without "boot ack" (bootstrap pin as per imx6q user manual, page 404, table, row 3, so with BOOT_CFG1[4] set), i can't boot anymore.

- eMMC is configured to boot from first boot sector EXT_CSD[179] set to boot from boot partition 1, and boot sector is correctly programmed and verified.

Strangely, with BOOT_CFG1[4] (Fast Boot) unset, i can boot from boot partition 1, as per EXT_CSD[179], but oscilloscope on CMD and data lines is not showing the fast boot to happen, so seems i am not actually into Fast Boot.

Every help is really appreciated.

Best regards.

Angelo

[igorpadykov]

Hi angelo

for Fast [BOOT_CFG1[4]] Boot option (max.50ms for obtaining first data) BOOT_ACK should be enabled

in eMMC EXT_CSD[179] bit 6 (0x1 : Boot acknowledge sent during boot operation).

Best regards

igor

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[angelo_d]

Hi Igor,

thanks i would clarify now once for all this "emmc" Fast Boot thing. I think imx6 datasheet should be eventually adjusted on option "naming" that can confuse the user.

1) there are 2 Fast Boot naming in the imx6q datasheet, but one is for SD Fast Boot and the other for eMMC. I try to clarify them below:

1. BOOT_CFG1[4] is for SD Fast Boot and must not be enabled for eMMC Fast Boot, or boot will hang on eMMC.
2. BOOT_CFG1[3:2] is related to eMMC Fast Boot Ack, should be enabled (i let it enabled)
3. BOOT_CFG2[1] seems related to eMMC and redundant for fast boot ack, i let it enabled too.

2) on eMMC side

1. EXT_CSD[179] must be set as 0x48, and boot program must be programmed in boot partition 1

Best regards

Angelo

[TheAdmiral]

Hi Angelo,

I think you left out an important register on the eMMC side that needs to be set:

EXT_CSD[177] must be programmed to match the BT_CFG settings used. The processor does not pass this information to the eMMC device, so the eMMC device needs to know it ahead of time.

I have a question into the SOC team to find out about the statement:

>> BOOT_CFG2[1] seems related to eMMC and redundant for fast boot ack,

I have my doubts that BOOT_CFG1[2] is really doing what the Reference Manual says it is.

And I think that CFG1[4] fast boot does apply to eMMC. In my discussions with the ROM expert, this fuse is followed for the primary boot, but if the customer chooses to use a secondary boot mode (redundent boot), then it is ignored and the eMMC will only perform a normal boot, from the general user space, looking at address 0x200.

Cheers,

Mark Middleton