Re: [PATCH] ath9k: fix TSF after reset on AR913x

[Felix Fietkau <nbd@openwrt.org>]

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