linux-kernel - RE: [PATCH 0/2] kxcjk-1013 driver optimizations

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Date:	Tue, 24 Feb 2015 17:22:12 +0000
From:	"Tirdea, Irina" <irina.tirdea@...el.com>
To:	Jonathan Cameron <jic23@...nel.org>,
	Peter Meerwald <pmeerw@...erw.net>
CC:	"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>,
	"Reus, Adriana" <adriana.reus@...el.com>
Subject: RE: [PATCH 0/2] kxcjk-1013 driver optimizations



> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23@...nel.org]
> Sent: 21 February, 2015 20:27
> To: Tirdea, Irina; Peter Meerwald
> Cc: linux-iio@...r.kernel.org; linux-kernel@...r.kernel.org; Pandruvada, Srinivas; Reus, Adriana
> Subject: Re: [PATCH 0/2] kxcjk-1013 driver optimizations
> 
> On 20/02/15 12:03, Tirdea, Irina wrote:
> >
> >
> >> -----Original Message-----
> >> From: Peter Meerwald [mailto:pmeerw@...erw.net]
> >> Sent: 16 February, 2015 21:14
> >> To: Tirdea, Irina
> >> Cc: Jonathan Cameron; linux-iio@...r.kernel.org; linux-kernel@...r.kernel.org; Pandruvada, Srinivas; Reus, Adriana
> >> Subject: Re: [PATCH 0/2] kxcjk-1013 driver optimizations
> >>
> >>
> >>> Adds optimization of i2c transactions in trigger handler and
> >>> usage of available_scan_masks for kxcjk-1013.
> >>
> >> the 'optimization' changes the capabilities of the driver, reading
> >> individual channel is not possible anymore
> >>
> > We can still read individual channels, just that the driver does not see that anymore and the demux is handled by the iio core.
> > available_scan_masks contains the bitmap superset for all channels we can enable (I will remove the 0 available_scan_mask as it
> does not makes sense).
> Careful. That's there as a null terminator for this list of available scan masks.
Missed this. You are right, thanks! Seems it's good as is.

> > When a new channel is enabled, the iio core checks if the new mask is a subset of any entry in available_scan_masks.
> > When the buffer is pushed from the driver, the iio core will select only the enabled channel values.
> 
> Pretty much.  IIRC This originally went in as part of handling multiple clients on these
> data streams, but it was rapidly pointed out that lots of drivers spun their own
> versions to break out particular elements from a multichannel read.
> As such, using the generic form saved on repetition in these cases as well.
> A good, complex example is drivers/iio/adc/max1363 in which really weird combinations
> of channels (but far from all) are available for bulk capture and reading.
> >
> >>> Adriana Reus (2):
> >>>   iio: accel: kxcjk-1013: use available_scan_masks
> >>>   iio: accel: kxcjk-1013: optimize i2c transfers in trigger handler
> >>>
> >>>  drivers/iio/accel/kxcjk-1013.c | 50 ++++++++++++++++++++++++++++++++----------
> >>>  1 file changed, 39 insertions(+), 11 deletions(-)
> >>>
> >>>
> >>
> >> --
> >>
> >> Peter Meerwald
> >> +43-664-2444418 (mobile)
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> > the body of a message to majordomo@...r.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >

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