From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Marek Vasut To: Hector Palacios Subject: Re: [PATCH 1/4] iio: mxs-lradc: change the realbits to 12 Date: Fri, 5 Jul 2013 15:10:28 +0200 Cc: "linux-iio@vger.kernel.org" , "alexandre.belloni@free-electrons.com" , "lars@metafoo.de" , "jic23@kernel.org" , "fabio.estevam@freescale.com" References: <1373013039-19461-1-git-send-email-hector.palacios@digi.com> <201307051337.39215.marex@denx.de> <51D6BED7.6060703@digi.com> In-Reply-To: <51D6BED7.6060703@digi.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Message-Id: <201307051510.29011.marex@denx.de> List-ID: Dear Hector Palacios, > Dear Marek, > > On 07/05/2013 01:37 PM, Marek Vasut wrote: > > Dear Hector Palacios, > > > >> The LRADC virtual channels have an 18 bit field to store the sum of up > >> to 2^5 accumulated samples. The read_raw function however only operates > >> over a single sample (12 bit resolution). > >> In order to use this field for scaling operations, we need it to be the > >> exact resolution value of the LRADC. > > > > How would this work once the accumulation is supported? > > As I see it, when you read a channel the driver should give you the 12-bit > value either of one single sample or of N samples. The hardware will always give you 18 bit value, let's call it A of N accumulated samples, each 12 bit long. N is in range of 1 to 32 . The driver currently supports N = 1. Do I understand it correctly that if we want to support N > 1, we have to do the division of A / N in the driver and therefore we will again report only a 12-bit value to the userland ? If so, Acked-by: Marek Vasut Best regards, Marek Vasut