Booting from eMMC on SAMA5D27 SOM based custom design.

Discussion around products based on ARM Cortex-A5 core.

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embeddedDevC
Posts: 5
Joined: Sun Aug 25, 2019 10:39 pm

Booting from eMMC on SAMA5D27 SOM based custom design.

Thu Oct 24, 2019 10:03 pm

We have designed a custom board using SAMA5D27 SOM module. We are having almost similar interfaces for sdmmc0 and sdmmc1 with little differences.
1) sdmmc0 interface is connected to eMMC and sdmmc1 interface is connected to sdcard.
2) Since sdmmc0 is connected to eMMC (non removable) we are not using card detection pin.

My question is Can ROM boot loader on SAMAD27 still detect the eMMC and boot from it?

Reason for the question:
I am able to boot successfully from the sdmmc1 (sdcard) but not from sdmmc0 (eMMC). On eMMC boot It's not proceeding further from ROMBOOT. Images built for SDMMC0 (eMMC) are successfully booting on SAMAD27 SOM1 EK1.

For debugging purpose I checked eMMC partition info and listed files for eMMC. Everything looked fine first partition is FAT16 and it has both boot.bin and u-boot.bin files and second partition have rootfs.

Also I used mmc utility to check the if eMMC has boot partition enabled or not, but all partitions of eMMC are boot disabled.

Need help to debug and proceed further on this and boot from eMMC.

Thanks.
blue_z
Location: USA
Posts: 2005
Joined: Thu Apr 19, 2007 10:15 pm

Re: Booting from eMMC on SAMA5D27 SOM based custom design.

Fri Oct 25, 2019 1:13 am

embeddedDevC wrote: ... we are not using card detection pin.
Simply mentioning one thing that you are "not using" or "not doing", which is an infinite list, is not as helpful as describing what you have actually done.

embeddedDevC wrote: My question is Can ROM boot loader on SAMAD27 still detect the eMMC and boot from it?
Maybe, maybe not.
Did you leave that sdmmc0 input floating?

FWIW an old revision of the SAMA5D2 had a SDMMC errata, so second-stage boot from SDMMC used to be avoided.
Hence the Linux4SAM demos for the ATSAMA5D2C-XULT do not boot from the eMMC.

Regards
embeddedDevC
Posts: 5
Joined: Sun Aug 25, 2019 10:39 pm

Re: Booting from eMMC on SAMA5D27 SOM based custom design.

Fri Oct 25, 2019 8:26 pm

Simply mentioning one thing that you are "not using" or "not doing", which is an infinite list, is not as helpful as describing what you have actually done.
We are not doing chip detection. Pin PA13 (SDMMC0 chip detection) is used for LED control in our design.
Did you leave that sdmmc0 input floating?
It's used as an output pin for LED control.

I am having a REV C SAMA5D27 module.
blue_z
Location: USA
Posts: 2005
Joined: Thu Apr 19, 2007 10:15 pm

Re: Booting from eMMC on SAMA5D27 SOM based custom design.

Sat Oct 26, 2019 12:16 am

embeddedDevC wrote: Pin PA13 (SDMMC0 chip detection) is used for LED control in our design.
It's used as an output pin for LED control.
There's your problem.
You can use the Device Tree to convey this pin configuration to the Linux kernel (and U-Boot).
But how do you expect to inform the ROM boot program of this nonstandard configuration?
The RomBOOT is expecting all the pins of sdmmc0 I/O Set 1 to be properly connected, and will configure PA13 as the input for a CD signal.

Regards

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