Comment # 24 on bug 900273 from Maxim Mikityanskiy

(In reply to Oliver Neukum from comment #21)
> (In reply to Takashi Iwai from comment #20)
> > Thanks for tracking down!
> > 
> > So, it comes from USB, but a specific device.  Oliver, any idea?
> 
> We might be hitting a race with the poll for medium change. Can you try with
> the attribute "events_poll_msecs" for the device in sysfs set to -1?

I experience the same problem on Lenovo Ideapad Z570, Gentoo, kernel 3.17.4. I
also use KDE and systemd. Sometimes laptop does not go to suspend, further
writes to /sys/power/state result in "Device or resourse busy", and I can't
rmmod rtsx_usb_sdmmc and bbswitch, rmmod just hangs in D state.

I inserted SD card, but events_poll_msecs does not appear:

max@ideapad ~ % ls -l /sys/block/mmcblk0/
total 0
-r--r--r-- 1 root root 4096 Dec  7 12:31 alignment_offset
lrwxrwxrwx 1 root root    0 Dec  7 12:31 bdi ->
../../../../../../../../../../../../virtual/bdi/179:0
-r--r--r-- 1 root root 4096 Dec  7 12:31 capability
-r--r--r-- 1 root root 4096 Dec  7 12:31 dev
lrwxrwxrwx 1 root root    0 Dec  7 12:31 device -> ../../../mmc0:0002
-r--r--r-- 1 root root 4096 Dec  7 12:31 discard_alignment
-r--r--r-- 1 root root 4096 Dec  7 12:31 ext_range
-rw-r--r-- 1 root root 4096 Dec  7 12:31 force_ro
drwxr-xr-x 2 root root    0 Dec  7 12:31 holders
-r--r--r-- 1 root root 4096 Dec  7 12:31 inflight
drwxr-xr-x 2 root root    0 Dec  7 12:31 power
drwxr-xr-x 3 root root    0 Dec  7 12:31 queue
-r--r--r-- 1 root root 4096 Dec  7 12:31 range
-r--r--r-- 1 root root 4096 Dec  7 12:31 removable
-r--r--r-- 1 root root 4096 Dec  7 12:31 ro
-r--r--r-- 1 root root 4096 Dec  7 12:31 size
drwxr-xr-x 2 root root    0 Dec  7 12:31 slaves
-r--r--r-- 1 root root 4096 Dec  7 12:31 stat
lrwxrwxrwx 1 root root    0 Dec  7 12:30 subsystem ->
../../../../../../../../../../../../../class/block
-rw-r--r-- 1 root root 4096 Dec  7 12:31 uevent

Instead, /sys/block/sda/events_poll_msecs exists, but it is hard drive, not the
card reader.