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
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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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:
2) on eMMC side
Best regards
Angelo
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