在 2016年04月28日 23:04, Eduardo Valentin 写道:
On Thu, Apr 28, 2016 at 09:50:29AM +0800, Caesar Wang wrote:
在 2016年04月28日 07:48, Eduardo Valentin 写道:
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
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Thanks,
Caesar
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Thanks,
Caesar
