* iio: adis16400 scan mask question
@ 2013-09-17 21:29 Peter Meerwald
2013-09-18 7:22 ` Lars-Peter Clausen
0 siblings, 1 reply; 3+ messages in thread
From: Peter Meerwald @ 2013-09-17 21:29 UTC (permalink / raw)
To: Lars-Peter Clausen; +Cc: linux-iio
Hello,
why the following code in drivers/iio/imu/adis16400_core.c?
static const unsigned long adis16400_burst_scan_mask[] = {
~0UL,
0,
};
[...]
if (!(st->variant->flags & ADIS16400_NO_BURST))
indio_dev->available_scan_masks = adis16400_burst_scan_mask;
isn't the all-1 scan mask the same as not applying any scan mask?
thanks, regards, p.
--
Peter Meerwald
+43-664-2444418 (mobile)
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: iio: adis16400 scan mask question
2013-09-17 21:29 iio: adis16400 scan mask question Peter Meerwald
@ 2013-09-18 7:22 ` Lars-Peter Clausen
2013-09-18 7:41 ` Peter Meerwald
0 siblings, 1 reply; 3+ messages in thread
From: Lars-Peter Clausen @ 2013-09-18 7:22 UTC (permalink / raw)
To: Peter Meerwald; +Cc: linux-iio
On 09/17/2013 11:29 PM, Peter Meerwald wrote:
> Hello,
>
> why the following code in drivers/iio/imu/adis16400_core.c?
>
> static const unsigned long adis16400_burst_scan_mask[] = {
> ~0UL,
> 0,
> };
>
> [...]
>
> if (!(st->variant->flags & ADIS16400_NO_BURST))
> indio_dev->available_scan_masks = adis16400_burst_scan_mask;
>
>
> isn't the all-1 scan mask the same as not applying any scan mask?
A scan mask where all bits are set means that sampling can only be done with
all channels enabled at once. Userspace can still only select a subset of
these channels and the kernel will take care of properly demuxing the stream.
- Lars
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: iio: adis16400 scan mask question
2013-09-18 7:22 ` Lars-Peter Clausen
@ 2013-09-18 7:41 ` Peter Meerwald
0 siblings, 0 replies; 3+ messages in thread
From: Peter Meerwald @ 2013-09-18 7:41 UTC (permalink / raw)
To: Lars-Peter Clausen; +Cc: linux-iio
> > if (!(st->variant->flags & ADIS16400_NO_BURST))
> > indio_dev->available_scan_masks = adis16400_burst_scan_mask;
> >
> > isn't the all-1 scan mask the same as not applying any scan mask?
> A scan mask where all bits are set means that sampling can only be done with
> all channels enabled at once. Userspace can still only select a subset of
> these channels and the kernel will take care of properly demuxing the stream.
ah, that's a pretty good reason
I discovered the demuxing code later-on
thanks, p.
--
Peter Meerwald
+43-664-2444418 (mobile)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-09-17 21:29 iio: adis16400 scan mask question Peter Meerwald
2013-09-18 7:22 ` Lars-Peter Clausen
2013-09-18 7:41 ` Peter Meerwald
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