On 05/09/2015 03:32 PM, Daniel Drake wrote:
Hi Champion,
I have a card here which has RTL8723BE wifi and bluetooth combined. 2 antennas.
In linux-next (Linux 4.2) the bluetooth and wifi work fine separately,
but when using them together, I can sometimes see a problem. This is
using the btusb driver based on your code (now included in Linux 4.2),
and the RTL8723B rtlwifi driver, all using the latest firmware in the
linux-firmware git repo.
To reproduce:
- Boot with no wifi connection active
- "hcitool scan" and verify that my laptop and phone can be seen
- Connect to wifi
- Run "hcitool scan" again a few times a minute, within 2-5 minutes
normally my phone and laptop can no longer be seen
- Disconnect from wifi and immediately run "hcitool scan" again, my
phone and laptop can be seen
3 interesting observations when the scan results are coming back empty:
1. I can still get the names of the remote devices by running
"hcitool name <addr>"
2. I can still query the remote devices by running "hcitool info
<addr>". After this, the scan suddenly starts working again!
3. Even though both of my local bluetooth devices no longer appear in
scan results, I can sometimes see my neighbour's phone coming up as a
scan result at this time.
Anyway, disabling btcoexist avoids the issue, so I dug through that
code, and found the exact line of code that seems to (sometimes) make
us enter this strange mode.
Call chain inside drivers/net/wireless/rtlwifi/btcoexist/halbtc8723b2ant.c:
ex_btc8723b2ant_bt_info_notify (called when starting and finishing a BT scan)
btc8723b2ant_run_coexist_mechanism
btc8723b2ant_action_bt_inquiry
As wifi is connected, we now call:
btc8723b2ant_ps_tdma(btcoexist, NORMAL_EXEC, true, 3);
This is the function call that sometimes puts us into the mode where
there are no scan results. Inside this function, if I comment out
these lines in the turn_on section, the bug is avoided:
case 3:
//btc8723b2ant_set_fw_ps_tdma(btcoexist, 0xe3, 0x1c,
// 0x3, 0xf1, 0x90);
break;
Any idea what is happening here? Can you help me find a better fix?
Daniel,
Do you see any adverse side effects when you comment out the "case 3" code?
As there has not been a lot of testing of wifi and BT with Realtek devices in
the field, I expect to see a number of bugs like this.
I added Shao Fu (aka Rock) to the Cc list. He is the Realtek engineer
responsible for the wifi driver.
Larry
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