From patchwork Tue Sep 17 13:51:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fabrice Gasnier X-Patchwork-Id: 11148909 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A191D14F7 for ; Tue, 17 Sep 2019 13:52:40 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 7E85B20678 for ; Tue, 17 Sep 2019 13:52:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="V8FDqdX0"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=st.com header.i=@st.com header.b="1pFlI5o2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E85B20678 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=st.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=wioG2tPvDaL+lXPVxYma/AWGsVX67EO1xyvcwF003Ns=; b=V8FDqdX0eyq9So aHkuGFNQjzkmxzkFbXeiNNnNCaReagNXBv+JAtPY69TEsKXeQVTwhRHt/biXm2g+ymBErZ4mSQE86 pAGNh3KcZkwrk84sDoFklwdGGcqjlzaU070dU/D38n+VV/ekVOsiqVwm+Yn3w/4IT8uDxYAyXSPCF x/VwZmJaJvYuToWRe5Ev0s1XxJNsU8cYCLEiv2eVVCENlpsyX0twne96vgmMWXcXZG0UMcgXmxITm bghCDSKMznyeeWuc05fQm1nTHudRGjn7pbTBxoBFJMPH6qA/dk9/RbZxvEuaeO6zl0akKtZi9n/wb HijnYZjS6sTvR7qronWA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iADuK-0004I7-0J; Tue, 17 Sep 2019 13:52:40 +0000 Received: from mx08-00178001.pphosted.com ([91.207.212.93] helo=mx07-00178001.pphosted.com) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1iADts-0003xD-4m for linux-arm-kernel@lists.infradead.org; Tue, 17 Sep 2019 13:52:14 +0000 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx08-00178001.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id x8HDfoKU019778; Tue, 17 Sep 2019 15:52:08 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : cc : subject : date : message-id : mime-version : content-type; s=STMicroelectronics; bh=aUuRSQwIFPiGfsmi4Vym/gWuxjE0wuSWUtUhECjq8Vc=; b=1pFlI5o2/+K+HEBbhT3MPTQXm7yxt3Gzo2eBe5uTkx372Kt7/Laxyj3Vtx+Gmx5fNMaY qloenvWqU1Z3UVZ6ob5J6SZGGLqzSFIEukHcJBFJDDgE6v7YkbEtGXsLmEsYc7CNERVZ oT52XBQFinU0phxaysyMRatRlMtYQluA14BOOpCfFdLgx0tRFA/o30A2zrnZ3IoZksSZ HvpJe2tLblTVSGlFARLU6FnIeFdgMiXsZN13jX37BGVkT5t+rqZfSPkt2C1mRwmhkn1t FN6KiqjXiAlHy01FMmU07yaqY5/IPOS0CTTzQa9WHDo5txYNt4tJw2rZJa18Bgu4XuIL pQ== Received: from beta.dmz-ap.st.com (beta.dmz-ap.st.com [138.198.100.35]) by mx08-00178001.pphosted.com with ESMTP id 2v0q3fspqm-1 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Tue, 17 Sep 2019 15:52:08 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-ap.st.com (STMicroelectronics) with ESMTP id 9777D4D; Tue, 17 Sep 2019 13:52:05 +0000 (GMT) Received: from Webmail-eu.st.com (Safex1hubcas23.st.com [10.75.90.46]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 068FE2C2B9A; Tue, 17 Sep 2019 15:52:05 +0200 (CEST) Received: from SAFEX1HUBCAS22.st.com (10.75.90.92) by SAFEX1HUBCAS23.st.com (10.75.90.46) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 17 Sep 2019 15:52:04 +0200 Received: from localhost (10.48.1.232) by Webmail-ga.st.com (10.75.90.48) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 17 Sep 2019 15:52:04 +0200 From: Fabrice Gasnier To: Subject: [PATCH] pwm: stm32-lp: add check in case requested period cannot be achieved Date: Tue, 17 Sep 2019 15:51:50 +0200 Message-ID: <1568728310-20948-1-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.48.1.232] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.70,1.0.8 definitions=2019-09-17_06:2019-09-17,2019-09-17 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190917_065212_950131_CACB0521 X-CRM114-Status: GOOD ( 13.57 ) X-Spam-Score: -0.9 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-0.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at https://www.dnswl.org/, low trust [91.207.212.93 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 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: linux-pwm@vger.kernel.org, alexandre.torgue@st.com, linux-kernel@vger.kernel.org, mcoquelin.stm32@gmail.com, fabrice.gasnier@st.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org LPTimer can use a 32KHz clock for counting. It depends on clock tree configuration. In such a case, PWM output frequency range is limited. Although unlikely, nothing prevents user from requesting a PWM frequency above counting clock (32KHz for instance): - This causes (prd - 1) = 0xffff to be written in ARR register later in the apply() routine. This results in badly configured PWM period (and also duty_cycle). Add a check to report an error is such a case. Signed-off-by: Fabrice Gasnier --- drivers/pwm/pwm-stm32-lp.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/pwm/pwm-stm32-lp.c b/drivers/pwm/pwm-stm32-lp.c index 2211a64..5c2c728 100644 --- a/drivers/pwm/pwm-stm32-lp.c +++ b/drivers/pwm/pwm-stm32-lp.c @@ -59,6 +59,12 @@ static int stm32_pwm_lp_apply(struct pwm_chip *chip, struct pwm_device *pwm, /* Calculate the period and prescaler value */ div = (unsigned long long)clk_get_rate(priv->clk) * state->period; do_div(div, NSEC_PER_SEC); + if (!div) { + /* Fall here in case source clock < period */ + dev_err(priv->chip.dev, "Can't reach expected period\n"); + return -EINVAL; + } + prd = div; while (div > STM32_LPTIM_MAX_ARR) { presc++;