From patchwork Tue Jun 23 19:58:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 223269 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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 159F9C433DF for ; Tue, 23 Jun 2020 21:09:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC7B820702 for ; Tue, 23 Jun 2020 21:09:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592946564; bh=XtFeMb8kGk3fuqPFWEzobBSlX/FA3bh16zbM1mW+u2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tG4FdOQ83Wwr4PGUt0BXLXWwnkoCPkkkCk2fxmV8ypHSjV0DAqcSHzh+szRHaCJis nga+hlclI2LMdZY1GzPMZBq64rqvt7gIkRLdnLll8BVQ3Ul1RKmY8NNRGB4FvDFrU6 6LdKh1unCmktr6f+j4fUdB0Ltxq6xMc07+HlIyvQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391513AbgFWUeQ (ORCPT ); Tue, 23 Jun 2020 16:34:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:56076 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391508AbgFWUeO (ORCPT ); Tue, 23 Jun 2020 16:34:14 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 4661A206C3; Tue, 23 Jun 2020 20:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592944454; bh=XtFeMb8kGk3fuqPFWEzobBSlX/FA3bh16zbM1mW+u2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lon8or8hv8Gdn3auoQvG3lYDdhknOWiBzkn2V8qqetY0F9xT6Sz0/MnacXjBrCArd 1ksWmwuQbyH3+TozvKdoj127B46rM7cVpHYa9SVoflbaCckX3Eb/g/BUICmRqQLVYt XlbzMBGGwkFnZ7rrVHxgH+Nelp3+y7nLQx6WXbE8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Paul Cercueil , Thierry Reding Subject: [PATCH 5.4 312/314] pwm: jz4740: Enhance precision in calculation of duty cycle Date: Tue, 23 Jun 2020 21:58:27 +0200 Message-Id: <20200623195353.884541761@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200623195338.770401005@linuxfoundation.org> References: <20200623195338.770401005@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paul Cercueil commit 9017dc4fbd59c09463019ce494cfe36d654495a8 upstream. Calculating the hardware value for the duty from the hardware value of the period resulted in a precision loss versus calculating it from the clock rate directly. (Also remove a cast that doesn't really need to be here) Fixes: f6b8a5700057 ("pwm: Add Ingenic JZ4740 support") Cc: Suggested-by: Uwe Kleine-König Reviewed-by: Uwe Kleine-König Signed-off-by: Paul Cercueil Signed-off-by: Thierry Reding [ukl: backport to v5.4.y and adapt commit log accordingly] Signed-off-by: Uwe Kleine-König Signed-off-by: Greg Kroah-Hartman --- drivers/pwm/pwm-jz4740.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/pwm/pwm-jz4740.c +++ b/drivers/pwm/pwm-jz4740.c @@ -108,8 +108,8 @@ static int jz4740_pwm_apply(struct pwm_c if (prescaler == 6) return -EINVAL; - tmp = (unsigned long long)period * state->duty_cycle; - do_div(tmp, state->period); + tmp = (unsigned long long)rate * state->duty_cycle; + do_div(tmp, NSEC_PER_SEC); duty = period - tmp; if (duty >= period)