From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D46AFC432BE for ; Tue, 17 Aug 2021 15:55:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCDCE60FD7 for ; Tue, 17 Aug 2021 15:55:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241099AbhHQP4O (ORCPT ); Tue, 17 Aug 2021 11:56:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:50800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240525AbhHQPwJ (ORCPT ); Tue, 17 Aug 2021 11:52:09 -0400 Received: from jic23-huawei (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D860B60C3E; Tue, 17 Aug 2021 15:51:18 +0000 (UTC) Date: Tue, 17 Aug 2021 16:54:18 +0100 From: Jonathan Cameron To: "hui.liu" Cc: Jonathan Cameron , , , , , , , , , , , , , , , Subject: Re: [PATCH v1 1/2] iio: mtk-auxadc: add support IIO_CHAN_INFO_RAW case Message-ID: <20210817165418.4b1cfdce@jic23-huawei> In-Reply-To: <470d4a7fbbcbcaa35aa9dcbaab6a2b77f98dc528.camel@mediatek.com> References: <20210812054844.30575-1-hui.liu@mediatek.com> <20210812054844.30575-2-hui.liu@mediatek.com> <20210812190725.00007449@Huawei.com> <042625639032bffe73b60a5c6274511e58e34ef4.camel@mediatek.com> <20210814171007.6892ae94@jic23-huawei> <470d4a7fbbcbcaa35aa9dcbaab6a2b77f98dc528.camel@mediatek.com> X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, 17 Aug 2021 16:37:52 +0800 hui.liu wrote: > On Sat, 2021-08-14 at 17:10 +0100, Jonathan Cameron wrote: > > On Fri, 13 Aug 2021 11:46:24 +0800 > > hui.liu wrote: > > > > > On Thu, 2021-08-12 at 19:07 +0100, Jonathan Cameron wrote: > > > > On Thu, 12 Aug 2021 13:48:43 +0800 > > > > Hui Liu wrote: > > > > > > > > > Add support IIO_CHAN_INFO_RAW case. > > > > > > > > Why? > > > > > > > > We almost never support both RAW and PROCESSED as userspace > > > > should be > > > > fine to use either. There are a few reasons we've let drivers do > > > > this but I would like know why it matters to you and it > > > > definitely > > > > needs to be in the patch description. > > > > > > > > > > Hi Jonathan, > > > > > > 1. To support ADC consumers' different types of requirement: some > > > consumers want to call iio_read_channel_raw to get raw data, the > > > others > > > use iio_read_channel_processed to get voltage. > > > > Give an example of the consumer using the raw channel readback > > (without > > acess to any scaling information?) > > > > > > 2. In our origin driver, if consumer call > > > iio_read_channel_processed, > > > read back value is raw data. > > > > > > Could we use SCALE instead of PROCESSED in patch for next version, > > > or > > > what's your suggestion? > > > > That would unfortunately be a userspace ABI change. We can add > > interfaces > > but taking them away is normally a problem :( > > > > Your reasons here are fine, subject to information on what consumer > > cares > > about having _RAW, please resend the patch with this information > > added > > to the description. > > > > Thanks, > > > > Jonathan > > 1. We found afe/iio-rescale.c, dac/dpot-dac.c and multiplexer/iio-mux.c > call iio_read_channel_raw to get raw data. If they use our ADC driver, > I think we should support _RAW case. > If we support _RAW case, we will add more information in v2 > description. iio-rescale has recently gained support for processed. https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/drivers/iio/afe/iio-rescale.c?h=testing&id=53ebee9499805add3eef630d998c40812e6a1c39 dpot-dac is a rather obscure special case, so I doubt you actually have one of those. If iio-mux is relevant then we should add processed support to that driver as well. I would rather see those users of the interface fixed than us having to tweak lots of drivers to provide _raw when it isn't appropriate for that piece of hardware. Jonathan > > 2. Since we change _PROCESSED readback value from raw data to voltage, > our consumer will make the changes synchronously. > > > > > > > Thanks. > > > > > > > > > > > > > Signed-off-by: Hui Liu > > > > > --- > > > > > drivers/iio/adc/mt6577_auxadc.c | 16 +++++++++++++++- > > > > > 1 file changed, 15 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/iio/adc/mt6577_auxadc.c > > > > > b/drivers/iio/adc/mt6577_auxadc.c > > > > > index 79c1dd68b909..e995d43287b2 100644 > > > > > --- a/drivers/iio/adc/mt6577_auxadc.c > > > > > +++ b/drivers/iio/adc/mt6577_auxadc.c > > > > > @@ -60,7 +60,8 @@ static const struct mtk_auxadc_compatible > > > > > mt6765_compat = { > > > > > .type = IIO_VOLTAGE, > > > > > > > > > > \ > > > > > .indexed = 1, > > > > > > > > > > \ > > > > > .channel = (idx), > > > > > \ > > > > > - .info_mask_separate = > > > > > BIT(IIO_CHAN_INFO_PROCESSED), \ > > > > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > > > > > > > > > > \ > > > > > + BIT(IIO_CHAN_INFO_PROCESS > > > > > ED), \ > > > > > } > > > > > > > > > > static const struct iio_chan_spec mt6577_auxadc_iio_channels[] > > > > > = { > > > > > @@ -181,6 +182,19 @@ static int mt6577_auxadc_read_raw(struct > > > > > iio_dev *indio_dev, > > > > > struct mt6577_auxadc_device *adc_dev = > > > > > iio_priv(indio_dev); > > > > > > > > > > switch (info) { > > > > > + case IIO_CHAN_INFO_RAW: > > > > > + *val = mt6577_auxadc_read(indio_dev, chan); > > > > > + if (*val < 0) { > > > > > + dev_notice(indio_dev->dev.parent, > > > > > + "failed to sample data on > > > > > channel[%d]\n", > > > > > + chan->channel); > > > > > + return *val; > > > > > + } > > > > > + if (adc_dev->dev_comp->sample_data_cali) > > > > > + *val = mt_auxadc_get_cali_data(*val, > > > > > true); > > > > > + > > > > > + return IIO_VAL_INT; > > > > > + > > > > > case IIO_CHAN_INFO_PROCESSED: > > > > > *val = mt6577_auxadc_read(indio_dev, chan); > > > > > if (*val < 0) { > > > > > > > > > > > >