Hello Ping-Ke Shih, thank you very much for your answer. Please find my comments below. Ping-Ke Shih <pkshih@xxxxxxxxxxx> wrote: > Does it mean 450ms on kernel 5.15, but 900ms on kernel 5.4 for RTL8822ce? [Jesuiter, Henry] Actually it's the following: * about 450ms for Kernel 6.8 (Ubuntu 24.04), i5-7300U * about 600ms for Kernel 6.6 (Buildroot), COMi.MX 6 * about 600ms for Kernel 5.15 (Ubuntu 20.04), i5-7300U * about 700ms - 900ms for Kernel 5.4 (Yocto 3.3.6), COMi.MX 6 For comparison: * roaming times of about 100ms on an ATH9k module (on an older HW revision), Kernel 5.4, Yocto 3.3.6, COMi.MX 6 > What is the WiFi card you are used to measure this roaming time? [Jesuiter, Henry ] We are using an Emwicon WMX6218 (WiFi 5, 802.11ac 2x2 MU-MIMO). > I measure rtw_leave_ips() which is to power on wifi card, and the cost is about 200ms in my x86 NB. [Jesuiter, Henry] Thanks for the measurement. So it's quite the same as on our x86 NB. > I measure rtw_chip_prepare_tx() which is to do phy calibration. The cost is about 190ms on 2GHz and 5GHz channels. [Jesuiter, Henry] This is the same function that is called on roaming, and we are experiencing similar results here. Thanks for the effort. > The costs I posted are hardware-related. Ignore IEEE80211_CONF_IDLE to avoid calling rtw_enter_ips()/rtw_leave_ips(), saving 200ms to power on hardware. [Jesuiter, Henry] We thought about that too, but we see no easy way to avoid the power down beforehand, since we are not able to distinguish a power down due to roaming from a power down due to other reasons. So - since the chip is powered down - we can't just skip the power up here. Any ideas are welcome 😉. > For PHY calibration, I think this is strictly necessary to get good performance. > One way may be deferred the calibration after getting connected, but 4 way and DHCP (right after getting connected) may not work well result from bad RF signal quality. [Jesuiter, Henry] Thanks for the consideration, we have similar concerns - especially regarding the EAPOL stuff. One more question. Is there a way to use 802.11r (fast roaming) with the mainline driver? Kind regards Henry Jesuiter
