Jes Sorensen <jes.sorensen@xxxxxxxxx> writes: > On 8/5/19 9:14 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 Realtek driver >> at https://github.com/lwfinger/rtl8723bu, the same iperf test gets >> ~12Mbps or better. The signal strength is reported similarly around >> -40dBm. That's why we want to improve. >> >> After reading the source code of the rtl8xxxu driver and Realtek's, the >> major difference is that Realtek'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 Realtek's driver, the tx rate observed from >> wireshark under the same condition is almost 65Mbps or 72Mbps, which >> indicating that rtl8xxxu could still be further improved. >> >> Signed-off-by: Chris Chiu <chiu@xxxxxxxxxxxx> >> Reviewed-by: Daniel Drake <drake@xxxxxxxxxxxx> >> --- > > Looks good to me! Nice work! I am actually very curious if this will > improve performance 8192eu as well. > > Ideally I'd like to figure out how to make host controlled rates work, > but in all my experiments with that, I never really got it to work well. > > Signed-off-by: Jes Sorensen <Jes.Sorensen@xxxxxxxxx> This is marked as RFC so I'm not sure what's the plan. Should I apply this? -- https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
