ok, I added
blacklist=mmc_block
to the end of my /etc/default/grub file then ran "sudo grub2-mkconfig -o /boot/grub2/grub.cfg"
on rebooting I examined the grub commands and it showed the kernel was being booted with the blacklist option. This blacklist did not fix the problem. The card still is unrecognized after suspend. I removed the kernel option.
I also tried adding "blacklist=mmc_block blacklist=mmc_core blacklist=rtsx_pci_sdmmc" to grub when booting with no effect. modinfo shows mmc_block and rtsx_pci_sdmmc both depend on mmc_core
before suspend, as root, these commands attach and detach the SD card successfully:
echo -n mmc0:aaaa > /sys/bus/mmc/drivers/mmcblk/bind
echo -n mmc0:aaaa > /sys/bus/mmc/drivers/mmcblk/unbind
After suspend, the above commands give the error "bash: echo: write error: No such device"
before the first suspend:
"sudo modprobe -r mmc_block" doesn't have much effect when the SD card is removed.
This command resets the machine if the SD card is inserted and attached.
after the first suspend:
sudo modprobe -r mmc_block
and
sudo modprobe mmc_block
don't seem to have any effect.