On Thu, May 6, 2010 at 8:38 PM, Helmut Schaa <helmut.schaa@xxxxxxxxxxxxxx> wrote: > Am Donnerstag 06 Mai 2010 schrieb Ivo Van Doorn: >> On Thu, May 6, 2010 at 12:29 PM, Helmut Schaa >> <helmut.schaa@xxxxxxxxxxxxxx> wrote: >> > Currently the CCK and OFDM SIFS value is set to 32us. This value is neither >> > used by the Ralink driver nor specified in 802.11. >> > >> > Instead of using 10us for CCK SIFS (as defined in 802.11) use 16us like in the >> > Ralink drivers. And indeed using a SIFS value of 10us breaks connectivity with >> > 11g + CTS protected connections. Add a comment to the code why we don't use 10us >> > for CCK SIFS value. >> > >> > The OFDM SIFS value is set to 16us (as defined in 802.11 and also used by the >> > Ralink drivers). >> >> Just wondering, but we hardcode the SIFS value in the rt2x00.h file. >> Perhaps we should remove it in there, and no longer pass it from >> rt2x00lib. That way there can't be any confusion about which drivers >> uses the sifs field and whcih do not. > > Yes, wouldn't be too bad I guess. But all non 2800 drivers use the same sifs > value, so we could just leave the define in rt2x00.h and remove the sifs value > from the config_erp calback and use the define in all other places? Well I would still remove the define in that case. I think some of the legacy drivers work with different SIFS values but always accepted the value which we used in the define. So I would still remove the define, and then each driver is free to set the value as used in the legacy drivers. > Nevertheless, I'm not sure why the rt2800 devices don't like the 10us CCK > SIFS value (which is defined in 802.11) but I wasn't able to get CTS to self > working correctly with it set to 10 (the actual data frame was sent out > way too late after the CTS frame, somtimes with delays >100us). Using the 16us > also for CCK (as the ralink drivers do) results in perfect CTS & data frame > timing. Maybe it's a hardware issue and the (ralink) driver just works around > it? Yes, I expect it to be case. This kind of odd values are used in the legacy drivers for other settings as well. Ivo -- 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
