SDIO cards may need clock to send the card interrupt to the host.

On a cherrytrail tablet with a RTL8723BS wifi chip, without this patch
pinging the tablet results in:

PING 192.168.1.14 (192.168.1.14) 56(84) bytes of data.
64 bytes from 192.168.1.14: icmp_seq=1 ttl=64 time=78.6 ms
64 bytes from 192.168.1.14: icmp_seq=2 ttl=64 time=1760 ms
64 bytes from 192.168.1.14: icmp_seq=3 ttl=64 time=753 ms
64 bytes from 192.168.1.14: icmp_seq=4 ttl=64 time=3.88 ms
64 bytes from 192.168.1.14: icmp_seq=5 ttl=64 time=795 ms
64 bytes from 192.168.1.14: icmp_seq=6 ttl=64 time=1841 ms
64 bytes from 192.168.1.14: icmp_seq=7 ttl=64 time=810 ms
64 bytes from 192.168.1.14: icmp_seq=8 ttl=64 time=1860 ms
64 bytes from 192.168.1.14: icmp_seq=9 ttl=64 time=812 ms
64 bytes from 192.168.1.14: icmp_seq=10 ttl=64 time=48.6 ms

Where as with this patch I get:

PING 192.168.1.14 (192.168.1.14) 56(84) bytes of data.
64 bytes from 192.168.1.14: icmp_seq=1 ttl=64 time=3.96 ms
64 bytes from 192.168.1.14: icmp_seq=2 ttl=64 time=1.97 ms
64 bytes from 192.168.1.14: icmp_seq=3 ttl=64 time=17.2 ms
64 bytes from 192.168.1.14: icmp_seq=4 ttl=64 time=2.46 ms
64 bytes from 192.168.1.14: icmp_seq=5 ttl=64 time=2.83 ms
64 bytes from 192.168.1.14: icmp_seq=6 ttl=64 time=1.40 ms
64 bytes from 192.168.1.14: icmp_seq=7 ttl=64 time=2.10 ms
64 bytes from 192.168.1.14: icmp_seq=8 ttl=64 time=1.40 ms
64 bytes from 192.168.1.14: icmp_seq=9 ttl=64 time=2.04 ms
64 bytes from 192.168.1.14: icmp_seq=10 ttl=64 time=1.40 ms

Cc: Dong Aisheng <b29396@freescale.com>
Cc: Ian W MORRISON <ianwmorrison@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>