Re: [PATCH 4/4] rt2x00: Report RX end time for rt2400pci

[Ivo van Doorn <ivdoorn@gmail.com>]

On Friday 04 July 2008, Johannes Berg wrote:
> 
> >  	rt2x00_desc_read(entry_priv->desc, 0, &word0);
> >  	rt2x00_desc_read(entry_priv->desc, 2, &word2);
> >  	rt2x00_desc_read(entry_priv->desc, 3, &word3);
> > +	rt2x00_desc_read(entry_priv->desc, 4, &word4);
> >  
> >  	if (rt2x00_get_field32(word0, RXD_W0_CRC_ERROR))
> >  		rxdesc->flags |= RX_FLAG_FAILED_FCS_CRC;
> > @@ -1106,6 +1108,7 @@ static void rt2400pci_fill_rxdone(struct queue_entry *entry,
> >  	 * The signal is the PLCP value, and needs to be stripped
> >  	 * of the preamble bit (0x08).
> >  	 */
> > +	rxdesc->timestamp = rt2x00_get_field32(word4, RXD_W4_RX_END_TIME);
> 
> You really should extend that, like this it's going to cause trouble as
> soon as it has overflowed 32 bits once.

Ok, but if I do the get_tsf() callback, to grab the upper 32 bytes of the timestamp,
you will get the same problems during wraparounds, because the upper 32 bytes
can be from _after_ the wrapround while the lower 32 bytes from the descriptor
are still from _before_ the wraparound.

Ivo