Johannes Stezenbach wrote: > On Mon, Sep 26, 2005 Oliver Endriss wrote: > > hunold@xxxxxxxxxxx wrote: > > > > > > First of all, I did not add "short_delay" to that code. ;-) > > > > I did, see below. > > Did you? Or do you confuse short_delay with SAA7146_I2C_SHORT_DELAY? Correct, I did not add short_delay. ;-) short_delay was added by Holger in rev 1.20. udelay(10) was added by Holger in 1.19. schedule_timeout() was introduced by Michael in 1.8. > It's pretty clear why SAA7146_I2C_SHORT_DELAY exists and waht it does, > but I don't get why short_delay exists, i.e. why using udelay(10) > instead of msleep(1) isn't the default. > > > Sorry, this is not correct. SAA7146_I2C_SHORT_DELAY turns on polling for > > _all_ transfers. (That's the reason why it had been added.) > > > > | if ( count > 3 || 0 != (SAA7146_I2C_SHORT_DELAY & dev->ext->flags) ) > > | short_delay = 1; > > > > SAA7146_I2C_SHORT_DELAY was introduced by me because tuning with FF > > cards was rather slow. From Changelog: > > > > | 2003-11-25 20:13 endriss > > | * linux/: drivers/media/common/saa7146_i2c.c, > > | drivers/media/dvb/ttpci/av7110.c, include/media/saa7146.h: > > | introduced flag SAA7146_I2C_SHORT_DELAY to speed up I2C access > > > > Before that, only larger transfers used polling. Since DVB cards use a > > lot of small i2c transfers there was noticeable delay during tuning. > > This is incorrect, the driver always uses polling, just one time > with msleep(1) (i.e. sleep at least one scheduler tick) and the other > with udelay(1) (busy loop for 10 usecs). You are right. s/polling/sleeping/. > > Imho the flag SAA7146_I2C_SHORT_DELAY should be added for all > > saa7146-based cards. > > Unless someone can explain why short_delay==0 is necessary I vote > for removing this altogether and making the use of udelay(10) > the default. Ack. Oliver -- -------------------------------------------------------- VDR Remote Plugin available at http://www.escape-edv.de/endriss/vdr/ --------------------------------------------------------
