? 2016?04?28? 23:04, Eduardo Valentin ??: > On Thu, Apr 28, 2016 at 09:50:29AM +0800, Caesar Wang wrote: >> >> ? 2016?04?28? 07:48, Eduardo Valentin ??: >>> On Mon, Apr 18, 2016 at 11:35:56AM +0800, Caesar Wang wrote: >>>> + regmap_write(grf, GRF_TSADC_TESTBIT_L, GRF_TSADC_TSEN_PD_ON); >>>> + mdelay(10); >>>> + regmap_write(grf, GRF_TSADC_TESTBIT_L, GRF_TSADC_TSEN_PD_OFF); >>>> + udelay(100); /* The spec note says at least 15 us */ >>>> + regmap_write(grf, GRF_SARADC_TESTBIT, GRF_SARADC_TESTBIT_ON); >>>> + regmap_write(grf, GRF_TSADC_TESTBIT_H, GRF_TSADC_TESTBIT_H_ON); >>>> + udelay(200); /* The spec note says at least 90 us */ >>> Does it make sense to use usleep_range() instead? >> I think so in the past, but I'm digging into the the udelay/usleep for >> kernel. > What do you mean by in the past? timekeeping doc still recommends the > range 10us to 20ms for usleep_range() > >> In general, >> >> udelay < 10us ~100us >> mdelay > 1m, <1000ms/HZ >> usleep_range(min,max) > 100us, <20ms > even here, your udelays could be replaced by usleep_range(). > > Any particular reason you believe spining is better than sleeping in > your case? > >> msleep > 20ms, < 1000ms >> >> So the udelay is suit for tsadc power sequence. >> --- >> >> >> Also, we have used the mdelay(10), so it doesn't matter if use the udelay. >> After all the udelay is stable than the usleep_range. > What do you mean udelay is stable than usleep_range? usleep_range will > give the opportunity to the scheduler to coalesce wakeups. udelay is a > busyloop spin. Besides, I am not sure the current situation, but > busylooping may be affected by cpu frequency. Okay, thanks for pointing out. Send the fixes patch on https://patchwork.kernel.org/patch/8999971/ Thank you! -Caesar > >> -Caesar >> >>> 1.9.1 >>> >>> >>> >>> >>> -- >>> Thanks, >>> Caesar > _______________________________________________ > Linux-rockchip mailing list > Linux-rockchip at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-rockchip -- Thanks, Caesar
