AM335x eMMC MMC0 boot

Alessandro Morgan

Dear All,

We've been trying to boot AM335x from eMMC 4GB connected to MMC0 interface.

What it seems to happen is that AM335x uses only Byte Mode to access eMMC, while the eMMC in our board requires Sector Access mode.

It that right?

How could we get out of this issue?

Thank you.

Kind Regards.

Alessandro Morgan.

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Alessandro,

Please check AM335X Technical Reference Manual, section 26.1.7.5.2.

0 li feiliang over 11 years ago

Prodigy 40 points

I also have encountered this. Maybe is inand flash bug. The 4GB inand flash ack OCR regester value 0x00ff8080 but the correct value should be 0x40ff8080 when send cmd1 with arg value 0. am335x send cmd1 with arg 0x00ff8080 that previous acked ,then inand enter "Inactive state" according to JEDEC STANDARD.

0 Biser Gatchev-XID over 11 years ago in reply to li feiliang

TI__Guru**** 393215 points

Please read section 26.1.7.5.2 of the AM335X Technical Reference Manual Rev. K. Booting from eMMC devices with size 4GB or greater is supported only on MMC1.

0 quan liang over 10 years ago in reply to Biser Gatchev-XID

Prodigy 130 points

hi，Biser. I have read the section 26.1.7.5.2 of TRM; it says that “the restriction is a reslut of many eMMC devices not being compliant with the eMMC v4.41 specification”, does it means that if i use a eMMC device compliant with eMMC v4.41 , then it is OK that the MMC0 boot with a 4G eMMC devices ?

0 Biser Gatchev-XID over 10 years ago in reply to quan liang

TI__Guru**** 393215 points

We do not recommend using MMC0 for eMMC boot.

0 quan liang over 10 years ago in reply to li feiliang

Prodigy 130 points

hi，li feiliang. i am encountered the exactly same problem with you. did you fix you problem now? or be force to change the board design to boot from mmc1?

also i am still curious of that the emmc device stil can send the reponse to host when it is in "Inactive state"? cause when we use the oscilloscope to measuring the mmc0_cmd, and found that it always has the respone from emmc device when the host repeat the CMD1.

i guess you are also a chinese by your name ：）

0 Liron Rodavsky over 10 years ago in reply to Biser Gatchev-XID

Prodigy 190 points

Could you elaborate?

I am at the stage which I am required to boot from MMC0 with 4GB which supported MMC v4.41

Can I use MMC0?

The other options of booting from MMC1 are very limited I need also SPI0 UART0 and EMAC1 and those does not cover MMC1 in sysboot options

Regards

0 obo0000 over 9 years ago in reply to Liron Rodavsky

Prodigy 90 points

We are also working with an AM335x and are planning to attach an eMMC memory to MMC0 instead of an SD card.We can not use MMC1 as we use GPMC.

Why is this discouraged? Can anyone please explain?

Is it possible to have multiple partitions on the eMMC to use larger memories and have a small boot partition only?

Thank you for your help.

Regards

0 quan liang over 9 years ago in reply to obo0000

Prodigy 130 points

Q1:

cause the am335x mmc0 only can attach with 2G OR LESS than 2 G eMMC。 MMC0 do not completely follow the V4.41 mmc specification。

Q2:

large memories with small boot partiton is unuse, cause mmc0 IN am335x can NOT identify the emmc chip when its capacity is equal with or larger than 4G.

BR!

0 obo0000 over 9 years ago in reply to quan liang

Prodigy 90 points

Thank you for your clear answers! Now we can decide if 2G with MMC0 are sufficient. Our current setup with SD cards with 32G work fine with MMC0.

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