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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 1D5B3C4338F for ; Tue, 3 Aug 2021 03:18:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01D8860F9C for ; Tue, 3 Aug 2021 03:18:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233537AbhHCDSO (ORCPT ); Mon, 2 Aug 2021 23:18:14 -0400 Received: from regular1.263xmail.com ([211.150.70.205]:41550 "EHLO regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233436AbhHCDSN (ORCPT ); Mon, 2 Aug 2021 23:18:13 -0400 X-Greylist: delayed 487 seconds by postgrey-1.27 at vger.kernel.org; Mon, 02 Aug 2021 23:18:12 EDT Received: from localhost (unknown [192.168.167.70]) by regular1.263xmail.com (Postfix) with ESMTP id B2FEA947; Tue, 3 Aug 2021 11:09:48 +0800 (CST) X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-ADDR-CHECKED4: 1 X-SKE-CHECKED: 1 X-ABS-CHECKED: 1 X-ANTISPAM-LEVEL: 2 Received: from [172.16.12.8] (unknown [58.22.7.114]) by smtp.263.net (postfix) whith ESMTP id P4991T139770963339008S1627960187187438_; Tue, 03 Aug 2021 11:09:47 +0800 (CST) X-IP-DOMAINF: 1 X-UNIQUE-TAG: <65d4135603dfef771ba2a7a9f4dcf93d> X-RL-SENDER: david.wu@rock-chips.com X-SENDER: wdc@rock-chips.com X-LOGIN-NAME: david.wu@rock-chips.com X-FST-TO: linux-iio@vger.kernel.org X-RCPT-COUNT: 11 X-SENDER-IP: 58.22.7.114 X-ATTACHMENT-NUM: 0 X-System-Flag: 0 Subject: Re: [PATCH] iio: adc: rockchip_saradc: just get referenced voltage once at probe To: Jonathan Cameron , Simon Xue Cc: Jonathan Cameron , linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org, robh+dt@kernel.org, Johan Jonker , Heiko Stuebner , Lars-Peter Clausen , Peter Meerwald-Stadler , linux-iio@vger.kernel.org References: <20210802090929.37970-1-xxm@rock-chips.com> <20210802114222.00004f3d@Huawei.com> From: David Wu Message-ID: <36f6284f-6bc9-d5a4-aac8-5db8b1ecaae1@rock-chips.com> Date: Tue, 3 Aug 2021 11:09:47 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210802114222.00004f3d@Huawei.com> Content-Type: text/plain; charset=gbk; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi Jonathan, ÔÚ 2021/8/2 ÏÂÎç6:42, Jonathan Cameron дµÀ: > On Mon, 2 Aug 2021 17:09:29 +0800 > Simon Xue wrote: > >> From: David Wu >> >> The referenced voltage is not changed after initiation, so just only >> get referenced voltage once. > Hi David, > > Isn't this an external reference voltage? If so how do you know > it is not changed at runtime? It might be unlikely and not happen > on particular platforms, but that's not he same as saying it can never > happen. Clearly it's racey anyway if that does happen, but we definitely > don't expect frequent voltage changes. > The current regulator is not changed and not subject to external changes, this can reduce the getting voltage. Assuming that there will be changes in the future, we then add the notify of the regulator, so that the voltage change can be obtained. > Jonathan > >> >> Signed-off-by: Simon Xue >> Signed-off-by: David Wu >> --- >> drivers/iio/adc/rockchip_saradc.c | 16 +++++++++------- >> 1 file changed, 9 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c >> index f3eb8d2e50dc..cd33c0b9d3eb 100644 >> --- a/drivers/iio/adc/rockchip_saradc.c >> +++ b/drivers/iio/adc/rockchip_saradc.c >> @@ -49,6 +49,7 @@ struct rockchip_saradc { >> struct clk *clk; >> struct completion completion; >> struct regulator *vref; >> + int uv_vref; >> struct reset_control *reset; >> const struct rockchip_saradc_data *data; >> u16 last_val; >> @@ -105,13 +106,7 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev, >> mutex_unlock(&indio_dev->mlock); >> return IIO_VAL_INT; >> case IIO_CHAN_INFO_SCALE: >> - ret = regulator_get_voltage(info->vref); >> - if (ret < 0) { >> - dev_err(&indio_dev->dev, "failed to get voltage\n"); >> - return ret; >> - } >> - >> - *val = ret / 1000; >> + *val = info->uv_vref / 1000; >> *val2 = chan->scan_type.realbits; >> return IIO_VAL_FRACTIONAL_LOG2; >> default: >> @@ -410,6 +405,13 @@ static int rockchip_saradc_probe(struct platform_device *pdev) >> return ret; >> } >> >> + info->uv_vref = regulator_get_voltage(info->vref); >> + if (info->uv_vref < 0) { >> + dev_err(&pdev->dev, "failed to get voltage\n"); >> + ret = info->uv_vref; >> + return ret; >> + } >> + >> ret = clk_prepare_enable(info->pclk); >> if (ret < 0) { >> dev_err(&pdev->dev, "failed to enable pclk\n"); > > > >