On Wed, Feb 1, 2012 at 12:34 PM, Daniel Lezcano <daniel.lezc...@linaro.org> wrote: > > Hi Linus, > > While looking at the drivers/mfd/db8500-prcmu.c file I noticed: > > > 595 /* Grab the HW semaphore. */ > 596 while ((readl(PRCM_SEM) & PRCM_SEM_PRCM_SEM) != 0) > 597 cpu_relax(); > > > I was wondering why is cpu_relax needed here as readl does a memory barrier > ? I thought the cpu_relax function was related to the x86 to consume less > power with an optimization of the "rep nop" loops or/and do a memory > barrier. > > Should a busy-loop be always with cpu_relax ?
Last time we discussed it ar LAKML I think we came to the conclusion that while cpu_relax() has very little semantic meaning on ARM, it is still nice to have from a readability and maintenance point of view, since it is pretty clear what we're trying to do. But I will stand corrected... Yours, Linus Walleij _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
