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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 43BBCC3DA6E for ; Wed, 3 Jan 2024 12:20:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=WKr7auVuRlSEd3XeyF/C7rXF0oTbV6O66gEaENPkdSk=; b=PGZ5cTCiv03fPc 48GHIaEiG+q20PjPGmtT/PbudtTSAPEKaXwGnFqPwURiKJULynLS0akISnitPQOc9LhjOvPoCa+k+ jY1d96aSJxUYALi3I13eTCjS4Xu3bPC0ai0cNoqGSElEISE/KKcMccsFuQhhtGgQxxoFbUI1mQhNK udf73nqqtRjU8rsm31fQZqpWwaM213Y8EN0ivA5uMvQ5CMcOKcsqZZvZOwwlFNoqNJFlNfzMPVgns MeJ9JzgRKQkrnt+aafFc/hCNJDzQOWZH+fLSvrpc39NyLDCvZklATUn9vdLJE686p/H/x8QIdnIVm 1Cpkf5adSKc5ymKIcZLg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rL0EJ-00AnP3-2T; Wed, 03 Jan 2024 12:20:15 +0000 Received: from mail11.truemail.it ([217.194.8.81]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rL0EG-00AnNu-2s for linux-arm-kernel@lists.infradead.org; Wed, 03 Jan 2024 12:20:14 +0000 Received: from francesco-nb (93-49-2-63.ip317.fastwebnet.it [93.49.2.63]) by mail11.truemail.it (Postfix) with ESMTPA id C707428144; Wed, 3 Jan 2024 13:20:09 +0100 (CET) Date: Wed, 3 Jan 2024 13:20:05 +0100 From: Francesco Dolcini To: pratikmanvar09@gmail.com Cc: francesco@dolcini.it, festevam@gmail.com, jun.li@nxp.com, kernel@pengutronix.de, linux-arm-kernel@lists.infradead.org, linux-imx@nxp.com, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, oe-kbuild-all@lists.linux.dev, pratik.manvar@ifm.com, s.hauer@pengutronix.de, shawnguo@kernel.org, thierry.reding@gmail.com, u.kleine-koenig@pengutronix.de, xiaoning.wang@nxp.com Subject: Re: [PATCH v3] pwm: imx27: workaround of the pwm output bug Message-ID: <20240103122005.GA3347@francesco-nb> References: <20240103103421.GA3758@francesco-nb> <20240103110200.1018-1-pratikmanvar09@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240103110200.1018-1-pratikmanvar09@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240103_042013_092405_D1B42543 X-CRM114-Status: GOOD ( 16.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Hello Pratik, On Wed, Jan 03, 2024 at 04:32:00PM +0530, pratikmanvar09@gmail.com wrote: > From: Clark Wang > > This fixes the pwm output bug when decrease the duty cycle. > This is a limited workaround for the PWM IP issue TKT0577206. > > Root cause: > When the SAR FIFO is empty, the new write value will be directly applied > to SAR even the current period is not over. > If the new SAR value is less than the old one, and the counter is > greater than the new SAR value, the current period will not filp the > level. This will result in a pulse with a duty cycle of 100%. > > Workaround: > Add an old value SAR write before updating the new duty cycle to SAR. > This will keep the new value is always in a not empty fifo, and can be > wait to update after a period finished. > > Limitation: > This workaround can only solve this issue when the PWM period is longer > than 2us(or <500KHz). > > Reviewed-by: Jun Li > Signed-off-by: Clark Wang > Link: https://github.com/nxp-imx/linux-imx/commit/16181cc4eee61d87cbaba0e5a479990507816317 > Tested-by: Pratik Manvar > Signed-off-by: Pratik Manvar A very similar patch was already send in 2021 [1], did it had review comments not addressed? Please have a look. In general please refrain from sending a new patch version every other day, while every Linux kernel subsystem has different rules and a difference pace of development, in this specific case sending a v3 just adding your signed-off-by without allowing a little bit of time to wait for more feedback is just not sane. [1] https://lore.kernel.org/all/?q=dfn%3Adrivers%2Fpwm%2Fpwm-imx27.c+AND+b%3A%22Clark+Wang%22 Francesco _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel