On Saturday 13 June 2009, liqin.chen@xxxxxxxxxxxxx wrote: > Arnd Bergmann <arnd@xxxxxxxx> 写于 2009-06-10 01:18:20: > > > On Tuesday 09 June 2009, liqin.chen@xxxxxxxxxxxxx wrote: > > > > Having a working udelay() function is required for many > > drivers that are sensitive to timing, you should probably > > implement that at some point in the future. > > Add udelay() implement in code. so you use static inline void __delay(unsigned long loops) { __asm__ __volatile__ ( "1:\tsubi\t%0,1\n\t" "cmpz.c\t%0\n\t" "bne\t1b\n\t" : "=r" (loops) : "0" (loops)); } static inline void __udelay(unsigned long usecs) { __delay(usecs); } This is much better than before, but is far from exact in the __udelay() case. Please take a look at init/calibrate.c and how other architectures use loops_per_jiffy if you don't have an exact time source you can use. If you have a time source with microsecond resolution or better, just loop until the amount of microseconds has expired. Arnd <>< -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html