On 25.08.26 14:24, Hiago De Franco wrote: > Hi Andrei, > > On Sat, Aug 22, 2026 at 11:15:10AM +0200, Andrei Lalaev wrote: >> Hi Hiago, >> >> Thank you for the patches. >> >> From your cover letter I understood that SD card is supported. >> However whatever I try, I always get the following error: >> >> U-Boot 2026.07-00002-gbd5e3de2ed6a (Aug 22 2026 - 10:27:48 >> +0200)milkv_duo_256m >> >> DRAM: 256 MiB >> Core: 20 devices, 13 uclasses, devicetree: separate >> MMC: mmc@4310000: 0 >> Loading Environment from nowhere... OK >> In: serial@4140000 >> Out: serial@4140000 >> Err: serial@4140000 >> Net: >> Warning: ethernet@4070000 (eth0) using random MAC address - >> 16:21:8c:10:cd:96 >> eth0: ethernet@4070000 >> Hit any key to stop autoboot: 0 >> milkv_duo_256m# mmc info >> Card did not respond to voltage select! : -110 >> milkv_duo_256m# mmc rescan >> Card did not respond to voltage select! : -110 >> >> >> I tried 2 different SD cards and got the same result. >> >> Am I doing something wrong, or is there something else I need to configure? > > You are most likely missing this patch: > > https://lore.kernel.org/all/[email protected]/ > > This is needed in order to make the SD card work. This patch is already > merged on main branch, as commit 3a4a8963aace ("mmc: cv1800b_sdhci: > honor 'no-1-8-v' DT property"). > > Check this patch and let me know if it works now ;)
Thank you for your response:) I also tried the latest main branch (so all patches are definitely included) and had the same problem. I guess I somehow managed to fix the problem, so below I'll describe what I did and would like to hear your thoughts about it. When I generated `fip.bin` using precompiled binaries from fiptool repo [1], it started working most of the time. Previously I was using an FSBL manually generated using official SDK [2]. However, I would still occasionally get voltage select error and timeouts. So I started comparing FSBL and U-boot from Sophgo (2021.10) and I couldn't find any differences that could explain this behaviour. Today I found out that the kernel DTS configures the SD0_CLK pin to a different value [3]. By default, we have 0x48 in IOBLK_G10_REG_SD0_CLK register, but if I set it to 0x84 like kernel does, it magically starts to work all the time. I understand why increasing the drive strength fixed timeout issues, but I don't understand why I don't see the same problem with the U-Boot from Sophgo (2021.10). 1 - https://github.com/sophgo/fiptool 2 - https://github.com/milkv-duo/duo-buildroot-sdk-v2/tree/main 3 - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/riscv/boot/dts/sophgo/sg2002-milkv-duo256m.dts#n68 >> >> >> Best regards, >> Andrei Lalaev > > Regards, > Hiago. -- Best regards, Andrei Lalaev
