This is a temporary fix for RTS5129/RTS5139 USB MMC card reader on Linux 3.16+ kernels. On my Lonovo Yoga 13 running Ubuntu 15.10 with a 4.2.0-25-generic kernel I get the following errors.
Jan 27 22:27:53 ideapad-yoga-13 kernel: [ 48.108682] mmc0: tuning execution failed
Jan 27 22:27:53 ideapad-yoga-13 kernel: [ 48.108699] mmc0: error -22 whilst initialising SD card
This ocurred during a transition from 3.15 to 3.16 kernel, as a result of the staging/rts5139 driver (which worked with the RTS5129/RTS5139) being replaced by the newer rtsx driver (which does not work with the RTS5129/RTS5139). This project reverts back to the old drivers as a temporary measure to get things up and running again.
Firstly, make sure you have kernel headers and the build-essential package installed.
Checkout, build and install the replacement driver.
cd /tmp
git clone https://github.com/asymingt/rts5139.git
cd rts5139
make
sudo make install
Blacklist the problematic modules by adding the following lines to /etc/modprobe.d/blacklist.conf.
blacklist rtsx_usb_sdmmc
blacklist rtsx_usb_ms
blacklist rtsx_usb
Then, make sure you disable module autoloading (and also in the initial RAM filesystem)
sudo depmod -a
sudo update-initramfs -u
Reboot, and check to see if the card reader works.