Dear Reinhard Meyer, In message <4cc6aadc.8050...@emk-elektronik.de> you wrote: > > Then the define CONFIG_SYS_HZ should not be in every <board>.h since that > suggests that a board developer has some freedom there...
Agreed - there are historical reasons this has ever been changable at all. > and MOST IMPORTANT that some implementations of udelay() might > call reset_timer() and therefore break an outer timeout loop !!! Such implementations are inherently broken and need to be fixed. > It is also open if reset_timer() does actually reset the hardware timer > (e.g. tbu/tbl at PPC) - which would be messing up any time difference > calculation using get_ticks() - or does emulate that by remembering > the hardware value and subtracting it later in every subsequent > get_timer() call? This is an implementation detail. > 2. get_ticks() and friends operate at a higher rate (tbu/tbl for PPC). > Since they are defined as having 64 bits they MUST not wrap at 32 bits, > i.e. if the hardware provides only 32 bits, the upper 32 bits must be > emulated by software. Right. > Otherwise we have to document that get_ticks() cannot be used to get > 64 bit time differences. No. Such an implementation is broken and needs fixing. > If you really closely look at the various implementations of those > timers, you will easyly see the wide variations implemented there. Yes, I am aware of this :-( Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de ...though his invention worked superbly -- his theory was a crock of sewage from beginning to end. - Vernor Vinge, "The Peace War" _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot