LS1088ardb send data over UART in U-boot during boot

zeroqruel — Fri, 17 Jan 2025 12:38:37 GMT

Hello dear experts,

I need your support and suggestions for a problem I have. We have custom boards with several versions based on ls1088a-rdb. In one of these versions, we have SD/eMMC connection switched via mux from cpld, designed on the same line. If I activate the eMMC line from cpld before powering on the device, I can successfully see it in the "/dev/mmcblk0" path when I type "fdisk -l" in the user space. But I want to use the SD card for booting and then activate the eMMC.

I tried this in user space and switched the eMMC line by sending a command to CPLD from the ls1088 UART3(/dev/ttyS2) line. However, when I say "fdisk -l" I don't see any active mmc lines. When I examine the kernel output with dmesg I get this error: "

/dev/mmcblk0: Can't open blockdev
mmcblk0: error -110 requesting status
mmcblk0: recovery failed!

My first question here is, is it possible to activate emmc after uboot and kernel initialization?

Second question is can I send data to CPLD via UART later during the flexbuild u-boot boot phase? UART1(ttyS0) is console, UART3 connected to CPLD. Is it possible to send data via UART3 line in U-boot?

Re: LS1088ardb send data over UART in U-boot during boot

Oswalag — Wed, 29 Jan 2025 20:57:59 GMT

Hello,

Please explain more about the process you follow to "select" emmc instead of sd card and share the complete log file in .txt file to review it.

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LS1088ardb send data over UART in U-boot during boot

Re: LS1088ardb send data over UART in U-boot during boot