[PATCH 4/4] ath10k: fix spurious tx/rx during boot

Ben Greear greearb at candelatech.com
Wed Aug 24 10:20:34 PDT 2016

On 07/19/2016 03:34 AM, Michal Kazior wrote:
> HW Rx filters and masks are not configured
> properly by firmware during boot sequences. The
> MAC_PCU_ADDR1 is set to 0s instead of 1s which
> allows the HW to ACK any frame that passes through
> is misconfigured on boot as well.
> The combination of these bugs ended up with the
> following manifestations:
>  - "no channel configured; ignoring frame(s)!"
>    warnings in the driver
>  - spurious ACKs (transmission) on the air during
>    firmware bootup sequences
> The former was a long standing and known bug
> originally though mostly harmless.
> However Marek recently discovered that this
> problem also involves ACKing *all* frames the HW
> receives (including beacons ;). Such frames
> are delivered to host and generate the former
> warning as well.
> This could be a problem with regulatory compliance
> in some rare cases (e.g. Taiwan which forbids
> transmissions on channel 36 which is the default
> bootup channel on 5Ghz band cards). The good news
> is that it'd require someone else to violate
> regulatory first to coerce our device to generate
> and transmit an ACK.
> The problem could be reproduced in a rather busy
> environment that has a lot of APs. The likelihood
> could be increased by injecting an msleep() of
> 5000 or longer immediately after
> ath10k_htt_setup() in ath10k_core_start().
> The reason why the former warnings were only
> showing up seldom is because the device was either
> quickly reset again (i.e. during firmware probing)
> or wmi vdev was created (which fixes hw and fw
> states).
> It is technically possible for host driver to
> override adequate hw registers however this can't
> work reliably because the bug root cause lies in
> incorrect firmware state on boot (internal
> structure used to program MAC_PCU_ADDR1 is not
> properly initialized) and only vdev create/delete
> events can fix it. This is why the patch takes
> dummy vdev approach.
> This could be fixed in firmware as well but having
> this fixed in driver is more robust, most notably
> when thinking of users of older firmware such as
> 999.999.0.636.
> Reported-by: Marek Puzyniak <marek.puzyniak at tieto.com>
> Signed-off-by: Michal Kazior <michal.kazior at tieto.com>

I was looking at firmware to make sure that I fixed what I could there....

 From what I can tell, 10.4 should not have this bug.  Did you see this only
on 10.1/10.2 firmware?  It is of course possible that I am mis-understanding


Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

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