From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <5009668A.7090502@metafoo.de> Date: Fri, 20 Jul 2012 16:09:14 +0200 From: Lars-Peter Clausen MIME-Version: 1.0 To: Marek Vasut CC: linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jonathan Cameron , Wolfgang Denk , Juergen Beisert Subject: Re: [PATCH] IIO: Add basic MXS LRADC driver References: <1341368129-20468-1-git-send-email-marex@denx.de> <50081AC0.10703@metafoo.de> <201207192126.31772.marex@denx.de> <201207200418.41554.marex@denx.de> In-Reply-To: <201207200418.41554.marex@denx.de> Content-Type: text/plain; charset=ISO-8859-1 List-ID: On 07/20/2012 04:18 AM, Marek Vasut wrote: >> Dear Lars-Peter Clausen, > [...] > > One more thing I'm curious about. There's another ADC block on the CPU, called > HSADC (high-speed ADC). It can sample even up to 2Msamples/s. If I were to, say > -- sample at 100kHz and be able to DMA the results into memory -- is there any > way to push such results into userland somehow? Or how to operate such fast > beast? Proper support for high speed sampling is still something that's missing from IIO. You can't mmap your buffers, you can't splice a IIO data stream to another file descriptor, there is no support for zero copy. So your bottleneck will become that you have to copy lots of data around. But it is certainly something that will be added at some point. So implementing the driver as a IIO driver is definitely the right direction. - Lars From mboxrd@z Thu Jan 1 00:00:00 1970 From: lars@metafoo.de (Lars-Peter Clausen) Date: Fri, 20 Jul 2012 16:09:14 +0200 Subject: [PATCH] IIO: Add basic MXS LRADC driver In-Reply-To: <201207200418.41554.marex@denx.de> References: <1341368129-20468-1-git-send-email-marex@denx.de> <50081AC0.10703@metafoo.de> <201207192126.31772.marex@denx.de> <201207200418.41554.marex@denx.de> Message-ID: <5009668A.7090502@metafoo.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/20/2012 04:18 AM, Marek Vasut wrote: >> Dear Lars-Peter Clausen, > [...] > > One more thing I'm curious about. There's another ADC block on the CPU, called > HSADC (high-speed ADC). It can sample even up to 2Msamples/s. If I were to, say > -- sample at 100kHz and be able to DMA the results into memory -- is there any > way to push such results into userland somehow? Or how to operate such fast > beast? Proper support for high speed sampling is still something that's missing from IIO. You can't mmap your buffers, you can't splice a IIO data stream to another file descriptor, there is no support for zero copy. So your bottleneck will become that you have to copy lots of data around. But it is certainly something that will be added at some point. So implementing the driver as a IIO driver is definitely the right direction. - Lars