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. > > -Caesar > > >1.9.1 > > > > > > > > > >-- > >Thanks, > >Caesar
