On 7/27/07, Nick Andrew <nick-linuxtv@xxxxxxxxxxxxxxx> wrote: > On Thu, Jul 26, 2007 at 05:41:41PM +0400, Manu Abraham wrote: > > That said, the firmware download is not too lengthy, but the Host when > > handling 2 Transfers simultaeneously in both directions, the > > performance might be degraded according to the vendor, though they do > > not have actual figures. > > Can you serialize the two transfers with a mutex? Serialization is not the case here, although serialization is needed to handle the 2 demods The communication goes through the Bus interface to the first demod and from there to the second demod. ----------->Host------------>demod #0(MASTER)----------->demod #1(SLAVE) If the host has 2 handle the 2 communications simultaneously, since it has to handle the USB requests as well as control communication through demod#0 to demod#1 It the case of the 2 stage copy, what you do is: 1) download fw ---------->Host 2) copy fw from Host to demod #1 Host disables demod#0 during the operation (transparent) Host--------------->demod#1 so, the fw is temporarily cached in the Host, rather than a straight download as in the very first (err..) diagram Disabling the caching (ie fw copy, 2 stage process) causes an overhead to the BIU, which the vendor says could affect effeciency/performance. Here the firmware download in any case happens for one device at a time only. Therefore a serialization employing a mutex doesn't bring in any additional improvements as it _is_ already serialized. Manu _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
