From: Felix Fietkau <nbd@openwrt.org>
To: "Björn Smedman" <bjorn.smedman@venatech.se>
Cc: Pavel Roskin <proski@gnu.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
"Luis R. Rodriguez" <lrodriguez@atheros.com>,
"John W. Linville" <linville@tuxdriver.com>
Subject: Re: [PATCH] ath9k: fix TSF after reset on AR913x
Date: Thu, 01 Jul 2010 02:47:36 +0200 [thread overview]
Message-ID: <4C2BE5A8.9030003@openwrt.org> (raw)
In-Reply-To: <AANLkTim8NrVZfcJGi4NK_OhXBxEY0Lw9fdg1bcbzDU0X@mail.gmail.com>
On 2010-07-01 12:38 AM, Björn Smedman wrote:
> On Thu, Jul 1, 2010 at 12:02 AM, Pavel Roskin <proski@gnu.org> wrote:
>> On Wed, 2010-06-30 at 02:07 +0200, Felix Fietkau wrote:
>>> + if (AR_SREV_9100(ah) && (ath9k_hw_gettsf64(ah) < tsf)) {
>>> + tsf += 1500;
>>
>> Why 1500? Is it a magic number? It is a result of some measurement?
>> Can we have a define for it, please?
>
> Does the TSF always start counting from zero when the chip is reset?
> In that case maybe the "magic number" can be replaced with the return
> value from ath9k_hw_gettsf64() (which we call anyway).
No, the TSF value at this point is not accurate. It differs
semi-randomly by a few orders of magnitude from the time measured by the
CPU timer. The value I put in above is just an approximation, but since
making it completely accurate is impossible, I figured this is good
enough, especially since the value will most likely not deviate much
from what I've measured here.
- Felix
next prev parent reply other threads:[~2010-07-01 0:47 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-30 0:07 [PATCH] ath9k: fix TSF after reset on AR913x Felix Fietkau
2010-06-30 22:02 ` Pavel Roskin
2010-06-30 22:38 ` Björn Smedman
2010-07-01 0:47 ` Felix Fietkau [this message]
2010-07-01 6:39 ` Johannes Berg
2010-07-01 7:51 ` Felix Fietkau
2010-07-01 0:45 ` Felix Fietkau
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