On 2010-07-01 8:39 AM, Johannes Berg wrote: > On Thu, 2010-07-01 at 02:47 +0200, Felix Fietkau wrote: > >> 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. > > Are you sure it doesn't depend on CPU speed as well since the driver is > involved here? Or DMA speed? Yes, it depends on CPU speed, but there's not a lot of variation possible, because this only affects one, maybe two different SoC types with similar CPU speed, and a large part of the delay is probably constant because of udelay calls. As I said, being precise here is impossible anyway, this is only a workaround for a hw issue, and this simple approximation should not cause any problems for anything. Even if the AP's TSF jumps by a few microseconds, the clients will catch on to that pretty quickly. - Felix -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
