c5211e997e
Tx status reporting on mt7603 has a number of issues: - the hardware can alter the first rate index, but it is not reported to the driver - probing is very imprecise, because it alters the per-client rate set, but only considers info->status.rates for rate selection of a single probe packet - short/long GI selection has limitations, which are not accurately reported to mac80211 - if rates are changed while packets are in flight, tx status reports for the old rate set might be processed based on the new selection This led to very suboptimal rate selection with minstrel_ht. This patch completely reworks tx status reporting to get rid of these limitations: - Store the previous and current rate set in the driver + the TSF value at the time of the switch. - Use the tx status TSF value to determine which rate set needs to be used as reference. - Report only short or long GI rates for a single status event, not a mix. - The hardware reports the last used rate index. Use it along with the retry count to figure out what rate was used for the first attempt. - Use the same retry count value for all rate slots to make this calculation work. - Derive the probe rate from the current rateset instead of the skb cb - Do not wait for a status report for the probe frame before removing the probe rate from the rate table. Do it immediately after it was referenced in a tx status report. - Use the first half of the first rate retry budget for the probe rate in order to avoid using too many retries on that rate With this patch, throughput under bad link conditions is improved significantly, and there is a lot less rate fluctuation going on. Signed-off-by: Felix Fietkau <nbd@nbd.name>
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.