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Date: Mon, 16 Nov 2015 10:37:37 +0100 From: Marc Titinger <mtitinger@...libre.com> To: Jonathan Cameron <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>, knaack.h@....de, pmeerw@...erw.net Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org, mturquette@...libre.com, bcousson@...libre.com, ptitiano@...libre.com Subject: Re: [RFC 4/4] iio: ina2xx: add SOFTWARE buffer mode using an iio kfifo. On 14/11/2015 19:44, Jonathan Cameron wrote: > On 12/11/15 10:18, Marc Titinger wrote: >> On 10/11/2015 19:23, Lars-Peter Clausen wrote: >>> On 11/10/2015 05:07 PM, Marc Titinger wrote: >>>> Capture the active scan_elements into a kfifo. >>>> The capture thread will compute the remaining time until the next capture >>>> tick, and do an active wait (udelay). >>>> >>>> This will produce a stream of up to fours channels plus a 64bits >>>> timestamps (ns). >>>> >>>> # iio_readdev ina226 | od -x >>>> WARNING: High-speed mode not enabled >>>> 0000000 042f 0d5a 002e 010c 4be8 4eb4 0013 0000 >>>> 0000020 0430 0d5a 002e 010c a704 4f3e 0013 0000 >>>> 0000040 0430 0d5a 002e 010c b477 4fc7 0013 0000 >>>> 0000060 042f 0d5b 002e 010c 8052 5050 0013 0000 >>>> 0000100 042f 0d5b 002e 010c 5d92 50d8 0013 0000 >>>> 0000120 0430 0d5a 002e 010c fa59 515e 0013 0000 >>>> 0000140 0430 0d5b 002e 010c 95d2 51e5 0013 0000 >>>> >>>> Signed-off-by: Marc Titinger <mtitinger@...libre.com> >> >> Hi Lars, >> >>> >>> Interesting approach. I think if we are going to due this we want to make >>> this kind of emulation generic. Have you seen the software trigger and >>> configfs support patches[1] from Daniel? It kind of achieves the same as you >>> do, but using hrtimers. >> > >> I totally agree, let me have a look on those patches maybe I could >> add an active waiting scheme for platforms w/o hrtimers ? > I've no idea if this is a remotely common case any more but in theory > I'd have no objection to such a patch though I would like it to be > a stand alone trigger similar to that used in the patch Daniel has > submitted. > Yes, I've started looking into something like a 'polling' trigger class. I understand that I'd need to support triggered buffer mode in the driver in this case. The current patch is rather simple, but having a generic and documented solution seems a good idea. >>> >>>> >>>> --- >>>> Ina2xx does not support auto-increment, hence the capture threads sticks >>>> with single register reads instead of regmap_bulk_read. >>>> >>>> The proper scales must be applied to those raw register >>>> values, I'm in favor of doing the conversion in userland in a client plugin >>> >>> Yes, conversion should not be done in kernel space, we don't want to impose >>> the performance penalty on users which don't need it and you can typically >>> do it faster in userspace anyway where you have floats and SSE and what not. >>> >>>> for instance a sigrok >>> >>> Slightly OT, but do you already have some Sigrok IIO support? I have this >>> scheduled for end of the month, maybe we can align our strategies here and >>> avoid duplicated work. >> > >> How fortunate! I've started some preliminary work like cloning the >> demo driver into a skeletton for 'hardware/generic-iio/api.c', adding >> the build/ac plumbing, and linking to libiio with the idea of using >> iio_info to create a generic enumeration of the iio-context into >> sigrok channels. >> >> Now, I'm not familiar with Glib and it might not be my prio until a >> couple of weeks, so I'd be super happy to wait for you if you are >> keen to do that part :) >> >> What would be the best spot to chat about this ? >> > >> Marc. >> >> >>> >>> - Lars >>> >>> [1] https://lkml.org/lkml/2015/8/10/877 >>> >> >> -- >> 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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