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=-11.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 1923BC388F9 for ; Sun, 8 Nov 2020 15:19:11 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BA5FE206B2 for ; Sun, 8 Nov 2020 15:19:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="HyR5cO1X"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="q9I7aJ5F" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA5FE206B2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=xUnfa8Qy95wSJH4xGQyh0AYGO/bRmWnFYs7C1ocJmi8=; b=HyR5cO1XpzPuN+90oo25E5TY4 Oby2homw0Pb3esC4PhS2TUmkuHhLHLTGjgcRnW9zjYe/a2AkLOqojV7rF0crCW4xWElxmrVTWrZzm d69A+JwBMDgmd2OsmEqIEsljlksM/KQ1RCZ4Bfsj4bmoovZpxdZd33pHLl9cZssQar1QHKsuoV24M qhITZ7+wUps8B5fOsi7F8cbVutvomB765dWk/Yr+JBlciCdNGzLcFMh+05Pp3uh1ZWDRdjty/2M5r REc5ToLldB1mdu57kDQODlZ6Z3NpGLwbAL8NhsRs+cG71qKf4HvdPJsAmn875Tb3rmekMGjIeB4Ct luCTAkqHA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kbmSo-0005G4-70; Sun, 08 Nov 2020 15:18:42 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kbmSl-0005F2-VM for linux-arm-kernel@lists.infradead.org; Sun, 08 Nov 2020 15:18:40 +0000 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (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 0BECD206B2; Sun, 8 Nov 2020 15:18:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604848714; bh=0CKqtqq+aeOYU19z0fE06Ud/SoL1fEHH0qhlYS0YDvA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=q9I7aJ5FbsgvzNIO+z+3NEbam63dMAi7KBjxsSj5vfVcm4uc9lcktJmnH7JHQ9noV q7Pip2DbokpPTkthZV87efexmfNYuhUWO2FYwR/Y2ZTu3Qj7d+rZ6NirYkDD7QQOAd 6mnaOyVj4H/j+8PnbUxlJUOd0TwdrqqiOykqmhCU= Date: Sun, 8 Nov 2020 15:18:35 +0000 From: Jonathan Cameron To: Fabrice Gasnier Subject: Re: [PATCH] iio: adc: stm32-adc: adapt clock duty cycle for proper operation Message-ID: <20201108151835.5d78ebca@archlinux> In-Reply-To: <1604681846-31234-1-git-send-email-fabrice.gasnier@st.com> References: <1604681846-31234-1-git-send-email-fabrice.gasnier@st.com> X-Mailer: Claws Mail 3.17.7 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201108_101840_148159_02DB6939 X-CRM114-Status: GOOD ( 24.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: olivier.moysan@st.com, alexandre.torgue@st.com, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 6 Nov 2020 17:57:26 +0100 Fabrice Gasnier wrote: > For proper operation, STM32 ADC should be used with a clock duty cycle > of 50%, in the range of 49% to 51%. Depending on the clock tree, divider > can be used in case clock duty cycle is out of this range. > In case clk_get_scaled_duty_cycle() returns an error, kindly apply a > divider by default (don't make the probe fail). > > Signed-off-by: Fabrice Gasnier Hi Fabrice, This sounds like it's a fix for a situation in which the device is not currently working? If so, please let me know a fixes tag. Thanks, Jonathan > --- > drivers/iio/adc/stm32-adc-core.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c > index cd870c0..d64a9e8 100644 > --- a/drivers/iio/adc/stm32-adc-core.c > +++ b/drivers/iio/adc/stm32-adc-core.c > @@ -202,7 +202,7 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, > { > u32 ckmode, presc, val; > unsigned long rate; > - int i, div; > + int i, div, duty; > > /* stm32h7 bus clock is common for all ADC instances (mandatory) */ > if (!priv->bclk) { > @@ -226,6 +226,11 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, > return -EINVAL; > } > > + /* If duty is an error, kindly use at least /2 divider */ > + duty = clk_get_scaled_duty_cycle(priv->aclk, 100); > + if (duty < 0) > + dev_warn(&pdev->dev, "adc clock duty: %d\n", duty); > + > for (i = 0; i < ARRAY_SIZE(stm32h7_adc_ckmodes_spec); i++) { > ckmode = stm32h7_adc_ckmodes_spec[i].ckmode; > presc = stm32h7_adc_ckmodes_spec[i].presc; > @@ -234,6 +239,13 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, > if (ckmode) > continue; > > + /* > + * For proper operation, clock duty cycle range is 49% > + * to 51%. Apply at least /2 prescaler otherwise. > + */ > + if (div == 1 && (duty < 49 || duty > 51)) > + continue; > + > if ((rate / div) <= priv->max_clk_rate) > goto out; > } > @@ -246,6 +258,10 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, > return -EINVAL; > } > > + duty = clk_get_scaled_duty_cycle(priv->bclk, 100); > + if (duty < 0) > + dev_warn(&pdev->dev, "bus clock duty: %d\n", duty); > + > for (i = 0; i < ARRAY_SIZE(stm32h7_adc_ckmodes_spec); i++) { > ckmode = stm32h7_adc_ckmodes_spec[i].ckmode; > presc = stm32h7_adc_ckmodes_spec[i].presc; > @@ -254,6 +270,9 @@ static int stm32h7_adc_clk_sel(struct platform_device *pdev, > if (!ckmode) > continue; > > + if (div == 1 && (duty < 49 || duty > 51)) > + continue; > + > if ((rate / div) <= priv->max_clk_rate) > goto out; > } _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel