2010/11/24 Nick Kossifidis <mickflemm@xxxxxxxxx>: > 2010/11/24 Jonathan Guerin <jonathan@xxxxxxxxxxxx>: >> On Wed, Nov 24, 2010 at 5:09 AM, Nick Kossifidis <mickflemm@xxxxxxxxx> wrote: >>> Â* Extend get_default_sifs/slot_time to include timings for turbo >>> Âhalf and quarter rate modes. >>> >>> Â* AR5210 code for now uses timings already on core clock units >>> Âinstead of usecs so rename them (we 'll clean it up later). >>> >>> ÂSigned-off-by: Nick Kossifidis <mickflemm@xxxxxxxxx> >>> --- >>> Âdrivers/net/wireless/ath/ath5k/ath5k.h |  24 ++++++++++++-- >>> Âdrivers/net/wireless/ath/ath5k/pcu.c  |  52 ++++++++++++++++++++++++-------- >>> Âdrivers/net/wireless/ath/ath5k/qcu.c  |  16 +++++---- >>> Â3 files changed, 68 insertions(+), 24 deletions(-) >>> >>> diff --git a/drivers/net/wireless/ath/ath5k/ath5k.h b/drivers/net/wireless/ath/ath5k/ath5k.h >>> index 005cad0..e11fc8f 100644 >>> --- a/drivers/net/wireless/ath/ath5k/ath5k.h >>> +++ b/drivers/net/wireless/ath/ath5k/ath5k.h >>> @@ -226,16 +226,16 @@ >>> Â#define AR5K_INIT_USEC             39 >>> Â#define AR5K_INIT_USEC_TURBO          79 >>> Â#define AR5K_INIT_USEC_32           Â31 >>> -#define AR5K_INIT_SLOT_TIME          Â396 >>> -#define AR5K_INIT_SLOT_TIME_TURBO       Â480 >>> +#define AR5K_INIT_SLOT_TIME_CLOCK       Â396 >> >> This comes out as 9.9us (with a clock multiplier of 40), rather than 9 >> - should be 360? >> >>> +#define AR5K_INIT_SLOT_TIME_TURBO_CLOCK        Â480 >>> Â#define AR5K_INIT_ACK_CTS_TIMEOUT       Â1024 >> >> From a previous post I'd made: >> >> According to the 802.11-2007 spec document, the ACKTimeout value is >> (Section 9.2.8 ACK procedure): >> ACKTimeout = aSIFSTime + aSlotTime + aPHY-RX-START-Delay >> >> From Table 17-15âOFDM PHY characteristics, the values are: >> aSIFSTime = 16 >> aSlotTime = 9 >> aPHY-RX-START-Delay = 25 >> >> Therefore, ACKTimeout = 50 >> >> With a value of 1024, the ACKTIMEOUT is actually 25. >> >>> Â#define AR5K_INIT_ACK_CTS_TIMEOUT_TURBO        Â0x08000800 >>> Â#define AR5K_INIT_PROG_IFS           920 >>> Â#define AR5K_INIT_PROG_IFS_TURBO        960 >>> Â#define AR5K_INIT_EIFS             3440 >> >> From the 802.11-2007 Spec (9.2.10 DCF timing relations): >> The EIFS is derived from the SIFS and the DIFS and the length of time >> it takes to transmit an ACK Control frame at the lowest PHY mandatory >> rate by the following equation: >> EIFS = aSIFSTime + DIFS + ACKTxTime >> where ACKTxTime is the time expressed in microseconds required to >> transmit an ACK frame, including >> preamble, PLCP header and any additional PHY dependent information, at >> the lowest PHY mandatory rate. >> >> So, EIFS = 16 + 32 + 44 (ACKTX @ 24Mbps) = 92 >> or 16 + 32 + 60 (ACKTX @ 6Mbps) = 108 >> >> The current value is 86, which I guess is a nice midpoint, but is >> there any reasoning for this value? It should really be set to the >> longest value of 108, as an EIFS is only used when we have no >> information about a frame because it failed the checksum. >> >>> Â#define AR5K_INIT_EIFS_TURBO          6880 >>> -#define AR5K_INIT_SIFS             560 >>> -#define AR5K_INIT_SIFS_TURBO          480 >>> +#define AR5K_INIT_SIFS_CLOCK          560 >> >> This is wrong, when you divide by the clock rate, you get a SIFS of 14, not 16. >> >> Cheers, >> >> Jonathan >> > > All _CLOCK variables are left here temporarily until we clean up > AR5210 stuff later, i know it's wrong ;-) > Check out patch 16 that adds the new set_ifs_intervals, there we set > them property, i just left them here so that code can still compile. > Also have in mind that clock on g is not 40 but 44 (for b compatibility) so 396 is correct here (396/44 = 9). Anyway we clean it up + these are only for AR5210 that we still don't support, i just put a _CLOCK prefix so that they don't get mixed up with the correct definitions. Check out patch 16, it should be fine ;-) -- GPG ID: 0xD21DB2DB As you read this post global entropy rises. Have Fun ;-) Nick -- 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
