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SubjectRe: [PATCH] mac80211: Fix wrong channel bandwidths reported for aggregates
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On 19/07/2022 17:03, Adrian Chadd wrote:
> Hi!
>
> It's not a hardware bug. Dating back to the original AR5416 11n chip,
> most flags aren't valid for subframes in an aggregate. Only the final
> frame has valid flags. This was explicitly covered internally way back
> when.

Ah, thanks for the clarification! I see it in the datasheet for the
QCA9531, too, now. And thanks for the confirmation, that what we are
doing so far is not correct for ath9k.

Words 0+2 are valid for all RX descriptors, 0+2+11 valid for the last RX
descriptor of each packet and 0-11 for the last RX descriptor of an
aggregate or last RX descriptor of a stand-alone packet. Or in other
words, word 4, which contains the 20 vs. 40 MHz indicator, is invalid
for any aggregate sub-frame other than the last one. I can rename that
in the commit message.


Another approach that also came to my mind was introducing more explicit
flags in cfg80211.h's "struct rate_info", like a RATE_INFO_BW_UNKNOWN in
"enum rate_info_bw" and/or RATE_INFO_FLAGS_UNKNOWN in "enum
rate_info_flags". And setting those flags in ath9k_cmn_process_rate().

The current approach is smaller though, as it simply uses the already
existing flags. If anyone has any preferences, please let me know.

Regards, Linus

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