On Thu, Jul 10, 2008 at 12:46:42AM +0200, Wolfgang Denk wrote: > In message <[EMAIL PROTECTED]> you wrote: > > > > The TQMA31, as well as the mx32ads use the General Purpose Timer 1, > > which is feeded by a 32768 clock (possibly imx31_litekit and > > imx31_phycore with 32000 Hz? I don't know.). The prescale divider can > > only be an integer. 32768/1000 = non-integer. > > I think other architectures hav / had similar issues. See for example > the MIPS fixes that were added some time ago. > > > Currently, I see only one way to solve this: > > 1. Patch the common file cpu/arm1136/mx31/interrupts.c, function > > interrupt_init(), so that the prescaler divides by 33. > > Alternatively, also make the divider a board specific define. > > 2. Patch all mx31 board config header files with CFG_HZ 1000. > > 3. All mx31 boards have to be tested. > > Sounds like a plan. > > > And while we are at the timers: > > The udelay function is the next problem: > > udelay cannot go below 1/(32768 Hz) = 30.5 micros > > The current function inserts a theoretical nop if the requested usec > > value is below 1000. Therefore, IMHO, this timer is relatively > > imprecise, because the resulting delay is below 1 microsecond. > > IMHO, this all because of that slow input clock. > > How is this handled in Linux? I don't think they would let this go > through?
Linux uses the high frequency timer, or better said, the same timer with a high frequency input source. Regards, Sascha -- Pengutronix e.K. - Linux Solutions for Science and Industry ----------------------------------------------------------- Kontakt-Informationen finden Sie im Header dieser Mail oder auf der Webseite -> http://www.pengutronix.de/impressum/ <- ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ U-Boot-Users mailing list U-Boot-Users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/u-boot-users
