AM3352: boot from external SPI flash

Hello,

I'm the customer. When I try to boot using SPI flash, I see the messages:
SPL: Unsupported Boot Device!
SPL: failed to boot from all boot devices
### ERROR ### Please RESET the board ###

I've been diagnosing the issue with some additional debug output in u-boot-ti-staging\common\spl\spl.c
Output from the routine spl_ll_find_loader shows there is no bootable device that contains "spi". The list include MMC1, MMC2, MMC2_2, NAND, "eth device", "USB eth", and "UART".
Output from the routine boot_from_devices shows trying to boot from device #8 "MMC1" when the SD is inserted and device #11 NULL when the SD card is removed.

When I boot from an SD card, from the uboot command line I tried the "sf probe 0" command. The result is:
Failed to initialize SPI flash at 0:0

I can update the MLO executable in SPI flash, so it's probably configured correctly. Based on the debug output my best guess is MLO doesn't know about SPI flash.

We're using a Spansion s25fl216k. It's possible the device tree and/or pin mux aren't completely correct.

Is there perhaps a list of changes needed to enable booting from SPI flash?

Thanks,
Scott

Hi Scott,
Due to limited on-chip SRAM size for SPL on AM335x, it is almost impossible to have complet boot mode support in one default config in u-boot build. There used to be a separate config, i.e. <am335x_evm_spiboot_defconfig> for building u-boot for booting SPL/u-boot from SPI on AM335x EVM. Is there <am335x_evm_spiboot_defconfig> in your u-boot tree?
Best,
-Hong

Hi Hong,

We're using processor-sdk-06.03.00.106. The only "spiboot" file I see is am43xx_evm_qspiboot_defconfig. There's nothing for the am335x.

I've added several lines to our defconfig:
CONFIG_SPI_BOOT=y
CONFIG_SPI_LOAD=y
CONFIG_SPL_SPI_LOAD=y

The SPL boot devices now contain "SPI". Now when I try to boot, I see these messages:
Trying to boot from SPI
SPI probe failed.
SPL: failed to boot from all boot devices

The SD card as removed, so MLO was obviously loaded from SPI flash. However, MLO can't see the SPI flash and/or can't find u-boot.img.

Do you have any suggestions?

Thanks,
Scott

Hi Scott,
I just checked SDK 6.3 (u-boot 2019.01), and you're right <am335x_evm_spiboot_defconfig> is not included for some reason.
It looks like <am335x_evm_spiboot_defconfig> is in the recent SDK 7.3 (u-boot 2019.01).
software-dl.ti.com/.../index_FDS.html
Best,
-Hong

correction on typo: recent SDK 7.3 (u-boot 2020.01)

Hi Hong,

I downloaded that 7.3 SDK and I've been reviewing am335x_evm_spiboot_defconfig.

After adding diagnostic output, it appears MLO doesn't find the SPI flash / "jedec,spi-nor" driver.

Is there any troubleshooting documentation available?

Thanks,
Scott

Hi Scott,
I built u-boot with <am335x_evm_spiboot_defconfig> using AM335x SDK 7.3, and I'm attaching two log files captured on AM335x GP EVM for your reference:
1. am3_7.3_spi_flash.txt: spi flashing log for spi flashing booting from MMC card.
Note that
- I used MLO/u-boot.img default build from SDK6.3 for MMC boot. It seems there's an issue using "sf probe 0" @u-boot when I was using the MLO/u-boot.img default build from SDK7.3
- SPL flashed images are built with <am335x_evm_spiboot_defconfig> from SDK 7.3: MLO.byteswap, u-boot_spi.img (renamed from u-boot.img).
2. am3_7.3_spi_boot.txt: spi booting log

Hopefully this helps you enabling SPI on your board.
Best,
-Hong

=> sf probe 0
SF: Detected w25q64cv with page size 256 Bytes, erase size 4 KiB, total 8 MiB
=> sf erase 0 +100000
SF: 1048576 bytes @ 0x0 Erased: OK
=> fatload mmc 0 ${loadaddr} MLO.byteswap
40504 bytes read in 6 ms (6.4 MiB/s)
=> sf write ${loadaddr} 0 ${filesize}
device 0 offset 0x0, size 0x9e38
SF: 40504 bytes @ 0x0 Written: OK
=> fatload mmc 0 ${loadaddr} u-boot_spi.img
772416 bytes read in 69 ms (10.7 MiB/s)
=> sf write ${loadaddr} 0x20000 ${filesize}
device 0 offset 0x20000, size 0xbc940
SF: 772416 bytes @ 0x20000 Written: OK
=> 

U-Boot SPL 2020.01-dirty (Jun 25 2021 - 16:20:09 -0500)
Trying to boot from SPI


U-Boot 2020.01-dirty (Jun 25 2021 - 16:20:09 -0500)

CPU  : AM335X-GP rev 2.1
Model: TI AM335x EVM
DRAM:  1 GiB
WDT:   Started with servicing (60s timeout)
NAND:  0 MiB
MMC:   OMAP SD/MMC: 0
Loading Environment from SPI Flash... Invalid bus 0 (err=-19)
*** Warning - spi_flash_probe_bus_cs() failed, using default environment

<ethaddr> not set. Validating first E-fuse MAC
Net:   Could not get PHY for ethernet@4a100000: addr 0
eth0: ethernet@4a100000
Warning: usb_ether MAC addresses don't match:
Address in ROM is          de:ad:be:ef:00:01
Address in environment is  1c:ba:8c:f0:79:11
, eth1: usb_ether
Hit any key to stop autoboot:  2  0 
=> 

Hi Hong,

I finally got everything to work with the 6.03 sdk by adding these lines to my defconfig:
CONFIG_SPI_BOOT=y
CONFIG_SPL_SPI_LOAD=y
CONFIG_SPL_OS_BOOT=n
CONFIG_SPI_FLASH_MACRONIX=y
CONFIG_SPI_FLASH_SPANSION=y
CONFIG_SPI_FLASH_USE_4K_SECTORS=y

I found those config statements by following the error messages in the MLO source code and determining what was missing.

Thanks,
Scott