a9bb0b5157
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@endlessm.com> Reviewed-by: Daniel Drake <drake@endlessm.com> Acked-by: Jes Sorensen <Jes.Sorensen@gmail.com> Signed-off-by: Kalle Valo <kvalo@codeaurora.org> |
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| drivers | ||
| fs | ||
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| kernel | ||
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| samples | ||
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| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.