RE: [PATCH rtw-next 0/5] wifi: rtw88: pci: Support an older design, like RTL8821AE/RTL8812AE

[Ping-Ke Shih <pkshih@realtek.com>]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> This series extends rtw88_pci to support an older design, like
> RTL8821AE, RTL8812AE, RTL8723BE, etc.

The older design is own-bit ring, and the new is read/write index ring
with buffer descriptor. Can we use 'own-bit' instead of 'old' as the file
name ?

> 
> After this, another ~20 small patches can enable support for RTL8821AE
> and RTL8812AE.

Will you plan to implement RTL8723BE (you listed it above) in rtw88?

> Then rtl8821ae can be deleted from rtlwifi.

Luka asked me to merge AP mode for RTL8723BS, because the AP mode of staging
rtl8723bs can work well. If you decide to delete it from rtlwifi, please
make sure all features are implemented before deleting. However, I can't
say what the exactly all features are. 

[1] https://lore.kernel.org/linux-wireless/d6af5cebfa1a46e2bc2da662634766d7@realtek.com/T/#maa2a3e897d5d488d0219399f9555d88b9ef6504f

> rtw88 is not without problems, but in my experience it's more reliable
> with these two chips. In the 6-8 months I used this code, I observed
> these problems with rtw88:
> 
>  * The top speed is a bit lower: ~220 Mbps instead of ~300 Mbps. In the
>    case of TX, the difference is due to the EDCA parameters. rtw88 uses
>    the ones from mac80211 (rtw_conf_tx()), whereas rtlwifi uses its own
>    "turbo" values when there are not too many non-BE packets
>    (rtl8821ae_dm_check_edca_turbo()). Not sure why the RX speed is
>    lower.

Maybe you can try to compare them by VO or VI packets?

> 
>  * RTL8821AE RX speed gets limited to 70-100 Mbps sometimes. If I watch
>    a Youtube video with Bluetooth headphones for 10 minutes and then
>    switch to another wifi adapter while the video is playing, leaving
>    the RTL8821AE's wifi side idle, usually within 20 minutes it will
>    start to raise IMR_RDU when it reaches the end of the RX ring and
>    goes back to the beginning.

Does it still happen without Bluetooth? IIRC the rtw88 BT-coexistence 
mainly supports RTL8822BE and RTL8822CE. I believe the algorithm can
share with other chips, but control registers or additional settings might
be missing.

> 
>    It uses RX descriptor number 511, then number 0, then it doesn't
>    want to use number 1 for "a while". It raises IMR_RDU once or twice,
>    and only then it moves on to number 1, 2...
> 
>    Usually when it raises IMR_RDU there are 510 or 511 RX descriptors
>    available (out of 512), so it has no excuse.
> 
>    Once it has raised IMR_RDU the RX speed doesn't exceed 70-100 Mbps
>    anymore.

If driver can receive packets on time, how does it raise ISR_RDU? 
Is RX interrupt triggered on time?

> 
>    Powering off and on again, which happens a lot when the wifi
>    interface is idle, doesn't help.
> 
>    The only thing that seems to help is reloading the driver, but even
>    that may not always work.

I think reloading the driver and interface idle are very similar (almost
the same). No idea why they have different results. 

> 
>    Switching to another wifi adapter while playing some video is the
>    most reliable way to trigger the problem, but it can also happen
>    randomly, it just takes many hours.

Thanks for your effort. 

Ping-Ke