Interfacing (DSI, CSI, I2C, etc.) • Re: Trying to establish SDIO communication between RPI and FPGA.

Tried poll_once with new overlay /boot/firmware/config.txt by dropping "sdio" and included new overlay. The error is not shown. But below are few commands I tried, where I couldn't get SDIO on mmc1 message with custom SDIO overlay

root@raspberrypi:/home/pi# ls /sys/class/mmc_host/
mmc0 mmc1
root@raspberrypi:/home/pi# cat /sys/kernel/debug/mmc1/ios
clock: 0 Hz
vdd: 0 (invalid)
bus mode: 2 (push-pull)
chip select: 0 (don't care)
power mode: 0 (off)
bus width: 0 (1 bits)
timing spec: 0 (legacy)
signal voltage: 0 (3.30 V)
driver type: 0 (driver type B)
root@raspberrypi:/home/pi# ls /sys/bus/sdio/devices/
root@raspberrypi:/home/pi# dmesg | grep -i mmc
[ 1.188473] mmc-bcm2835 fe300000.mmc: mmc_debug:0 mmc_debug2:0
[ 1.188480] mmc-bcm2835 fe300000.mmc: DMA channel allocated
[ 1.253552] mmc0: SDHCI controller on fe340000.mmc [fe340000.mmc] using ADMA
[ 1.355072] mmc0: new ultra high speed DDR50 SDXC card at address 5048
[ 1.355600] mmcblk0: mmc0:5048 SD128 119 GiB
[ 1.360627] mmcblk0: p1 p2
[ 1.360898] mmcblk0: mmc0:5048 SD128 119 GiB (quirks 0x00004000)
[ 2.056248] EXT4-fs (mmcblk0p2): orphan cleanup on readonly fs
[ 2.057182] EXT4-fs (mmcblk0p2): mounted filesystem 0dfc4957-81ab-4994-96e7-7d41deb1b52f ro with ordered data mode. Quota mode: none.
[ 4.127708] EXT4-fs (mmcblk0p2): re-mounted 0dfc4957-81ab-4994-96e7-7d41deb1b52f r/w.

Statistics: Posted by medandi kavya — Tue Feb 24, 2026 5:19 am

---