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From: Felix Fietkau <nbd@openwrt.org>
To: "Luis R. Rodriguez" <lrodriguez@atheros.com>
Cc: linux-wireless@vger.kernel.org, linville@tuxdriver.com,
	Jouni Malinen <Jouni.Malinen@atheros.com>
Subject: Re: [PATCH 2/3] ath9k_hw: clean up per-channel calibration data
Date: Wed, 28 Jul 2010 23:30:24 +0200	[thread overview]
Message-ID: <4C50A170.1070902@openwrt.org> (raw)
In-Reply-To: <AANLkTi==nB+Wqe3KcmDf6P=JUYnLzc2PeAuOZQE3v9bn@mail.gmail.com>

On 2010-07-28 11:21 PM, Luis R. Rodriguez wrote:
> On Wed, Jul 28, 2010 at 2:10 PM, Felix Fietkau <nbd@openwrt.org> wrote:
>> On 2010-07-28 10:52 PM, Luis R. Rodriguez wrote:
>>> On Wed, Jul 28, 2010 at 10:45 AM, Felix Fietkau <nbd@openwrt.org> wrote:
>>>> The noise floor history buffer is currently not kept per channel, which
>>>> can lead to problems when changing channels from a clean channel to a
>>>> noisy one. Also when switching from HT20 to HT40, the noise floor
>>>> history buffer is full of measurements, but none of them contain data
>>>> for the extension channel, which it needs quite a bit of time to recover
>>>> from.
>>>>
>>>> This patch puts all the per-channel calibration data into a single data
>>>> structure, and gives the the driver control over whether that is used
>>>> per-channel or even not used for some channels.
>>>>
>>>> For ath9k_htc, I decided to keep this per-channel in order to avoid
>>>> creating regressions.
>>>>
>>>> For ath9k, the data is kept only for the operating channel, which saves
>>>> some space. ath9k_hw takes care of wiping old data when the operating
>>>> channel or its channel flags change.
>>>>
>>>> Signed-off-by: Felix Fietkau <nbd@openwrt.org>
>>>
>>> But this also means every time we want to get operational on a channel
>>> we have to learn the current noise all over again. This means for WiFi
>>> Direct every channel swap we'd have to learn to walk, which happens
>>> quite often. What do you think? Sorry, I know we discussed this
>>> approach and I seemed fine but this just occurred to me now, and will
>>> become really important later when we support WiFi Direct.
>> When we get to implementing per-vif channel settings with switching
>> being done in mac80211, we can just move the calibration data to ath9k's
>> virtual interface data and thus keep the calibration for multiple
>> operating channels.
> 
> Sounds good. This would currently break the ath9k virtual wiphy's
> calibration stuff :P (not like I care), Jouni?
My current patch should work just fine with virtual wiphy's, since I
store the calibration data in the ath_wiphy struct.

- Felix

  reply	other threads:[~2010-07-28 21:30 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-28 17:45 [PATCH 1/3] ath9k: prevent calibration during off-channel activity Felix Fietkau
2010-07-28 17:45 ` [PATCH 2/3] ath9k_hw: clean up per-channel calibration data Felix Fietkau
2010-07-28 17:45   ` [PATCH 3/3] ath9k_hw: fix a noise floor calibration related race condition Felix Fietkau
2010-07-28 20:52   ` [PATCH 2/3] ath9k_hw: clean up per-channel calibration data Luis R. Rodriguez
2010-07-28 21:10     ` Felix Fietkau
2010-07-28 21:21       ` Luis R. Rodriguez
2010-07-28 21:30         ` Felix Fietkau [this message]
2010-07-28 21:40           ` Luis R. Rodriguez
2010-07-28 22:03             ` Felix Fietkau
2010-07-28 20:43 ` [PATCH 1/3] ath9k: prevent calibration during off-channel activity Luis R. Rodriguez
2010-07-28 21:08   ` Felix Fietkau
2010-07-28 22:12     ` Luis R. Rodriguez
2010-07-28 22:28       ` Felix Fietkau
2010-07-28 22:47         ` Luis R. Rodriguez
2010-07-28 22:48           ` Luis R. Rodriguez
2010-07-29 16:58             ` wireless-next-2.6 rebase -- " John W. Linville

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