On Thu, May 30, 2019 at 2:22 AM Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote: > > On 5/29/19 12:03 AM, Chris Chiu wrote: > > We have 3 laptops which connect the wifi by the same RTL8723BU. > > The PCI VID/PID of the wifi chip is 10EC:B720 which is supported. > > They have the same problem with the in-kernel rtl8xxxu driver, the > > iperf (as a client to an ethernet-connected server) gets ~1Mbps. > > Nevertheless, the signal strength is reported as around -40dBm, > > which is quite good. From the wireshark capture, the tx rate for each > > data and qos data packet is only 1Mbps. Compare to the driver from > > https://github.com/lwfinger/rtl8723bu, the same iperf test gets ~12 > > Mbps or more. The signal strength is reported similarly around > > -40dBm. That's why we want to improve. > > The driver at GitHub was written by Realtek. I only published it in a prominent > location, and fix it for kernel API changes. I would say "the Realtek driver at > https://...";, and every mention of "Larry's driver" should say "Realtek's > driver". That attribution is more correct. Thanks. I'll modify this in next revision. > > > > After reading the source code of the rtl8xxxu driver and Larry's, the > > major difference is that Larry's driver has a watchdog which will keep > > monitoring the signal quality and updating the rate mask just like the > > rtl8xxxu_gen2_update_rate_mask() does if signal quality changes. > > And this kind of watchdog also exists in rtlwifi driver of some specific > > chips, ex rtl8192ee, rtl8188ee, rtl8723ae, rtl8821ae...etc. They have > > the same member function named dm_watchdog and will invoke the > > corresponding dm_refresh_rate_adaptive_mask to adjust the tx rate > > mask. > > > > With this commit, the tx rate of each data and qos data packet will > > be 39Mbps (MCS4) with the 0xF00000 as the tx rate mask. The 20th bit > > to 23th bit means MCS4 to MCS7. It means that the firmware still picks > > the lowest rate from the rate mask and explains why the tx rate of > > data and qos data is always lowest 1Mbps because the default rate mask > > passed is always 0xFFFFFFF ranges from the basic CCK rate, OFDM rate, > > and MCS rate. However, with Larry's driver, the tx rate observed from > > wireshark under the same condition is almost 65Mbps or 72Mbps. > > > > I believe the firmware of RTL8723BU may need fix. And I think we > > can still bring in the dm_watchdog as rtlwifi to improve from the > > driver side. Please leave precious comments for my commits and > > suggest what I can do better. Or suggest if there's any better idea > > to fix this. Thanks. > > > > Signed-off-by: Chris Chiu <chiu@xxxxxxxxxxxx> > > I have not tested this patch, but I plan to soon. > > Larry > >
