On Wed, 3 May 2006 21:05:53 +0200, Michael Buesch wrote:
> @@ -354,6 +354,33 @@
>       bcm43xx_write32(bcm, BCM43xx_MMIO_STATUS_BITFIELD, status);
>  }
>  
> +static void bcm43xx_measure_channel_change_time(struct bcm43xx_private *bcm)
> +{
> +     struct bcm43xx_radioinfo *radio;
> +     u64 start, stop;
> +     unsigned long flags;
> +     u8 oldchan, testchan;
> +
> +     /* We (ab)use the bcm43xx TSF timer to measure the time needed
> +      * to switch channels. This information is handed over to
> +      * the ieee80211 subsystem.
> +      * Time is measured in microseconds.
> +      */
> +
> +     bcm43xx_lock_mmio(bcm, flags);
> +     radio = bcm43xx_current_radio(bcm);
> +     oldchan = radio->channel;
> +     testchan = (oldchan == 6) ? 7 : 6;
> +     bcm43xx_tsf_read(bcm, &start);
> +     bcm43xx_radio_selectchannel(bcm, testchan, 0);
> +     bcm43xx_tsf_read(bcm, &stop);
> +     bcm43xx_radio_selectchannel(bcm, oldchan, 0);
> +     bcm43xx_unlock_mmio(bcm, flags);
> +
> +     assert(stop > start);

I think some safety fallback would be better. Like
if (stop - start < SOME_MIN_VALUE) channel_change_time = SOME_MIN_VALUE
(of course, this won't work because stop and start are unsigned, but you
probably got the idea).

And couldn't TSF counter overflow during the measurement?

> +     bcm->ieee->channel_change_time = stop - start;
> +}
> +
>  static
>  void bcm43xx_macfilter_set(struct bcm43xx_private *bcm,
>                          u16 offset,
> @@ -3706,6 +3733,7 @@

Please, could you use -p parameter when generating diffs for easier
review?

Thanks,

 Jiri

-- 
Jiri Benc
SUSE Labs
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