The RTL8723BU suffers the wifi disconnection problem while bluetooth
device connected. While wifi is doing tx/rx, the bluetooth will scan
without results. This is due to the wifi and bluetooth share the same
single antenna for RF communication and they need to have a mechanism
to collaborate.

BT information is provided via the packet sent from co-processor to
host (C2H). It contains the status of BT but the rtl8723bu_handle_c2h
dose not really handle it. And there's no bluetooth coexistence
mechanism to deal with it.

This commit adds a workqueue to set the tdma configurations and
coefficient table per the parsed bluetooth link status and given
wifi connection state. The tdma/coef table comes from the vendor
driver code of the RTL8192EU and RTL8723BU. However, this commit is
only for single antenna scenario which RTL8192EU is default dual
antenna. The rtl8xxxu_parse_rxdesc24 which invokes the handle_c2h
is only for 8723b and 8192e so the mechanism is expected to work
on both chips with single antenna. Note RTL8192EU dual antenna is
not supported.
Signed-off-by: Chris Chiu <chiu@endlessm.com>
Signed-off-by: Jes Sorensen <Jes.Sorensen@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>