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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 836C6CDB465 for ; Sat, 14 Oct 2023 06:51:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229518AbjJNGv2 (ORCPT ); Sat, 14 Oct 2023 02:51:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229958AbjJNGv1 (ORCPT ); Sat, 14 Oct 2023 02:51:27 -0400 Received: from mail-ej1-x62c.google.com (mail-ej1-x62c.google.com [IPv6:2a00:1450:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E58D1BF; Fri, 13 Oct 2023 23:51:25 -0700 (PDT) Received: by mail-ej1-x62c.google.com with SMTP id a640c23a62f3a-991c786369cso451260766b.1; Fri, 13 Oct 2023 23:51:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1697266284; x=1697871084; darn=vger.kernel.org; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject:from:to:cc :subject:date:message-id:reply-to; bh=vx7O+/mPyye+58XO3gfh4ede5Ey/i5cAVMi6RSAm2Fo=; b=eyom93PuMzfsRBELugxDlR2Fn26QgcRhWq4dav/jtTvJF4Cg4BqqBwrDltFOHUnwdV 19q1iqpKHF1uF0lpU9PU8Dv+PpqmkVeNNfOjGwQecN4/wIZMLE1TUBKUPAPDBW339sX8 VEsdV6UlIzgmebBtASK3E/jsWQGAyX9Gh7e/5W2cIQU9qiV5bVKrMj1T/ugDmght+7cz MFJxxi1spS0henp9x56z9uncH+dUZ19/yYNj4Mjzuzs7mKZUxcO91cMXt7WbshsL3jTd 5gMNBYV3kzzUdPmv+FWi+SUKkpooGvoZDnaf26eUGEEEc9mXU+6AJOL2l8U6HqOwKzWT Bisg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697266284; x=1697871084; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vx7O+/mPyye+58XO3gfh4ede5Ey/i5cAVMi6RSAm2Fo=; b=IcOIq5xQwCQ53a4YoRyzB0DlaHj2fjXNbhOh33qicgGmesRGI3dpw7aD9koiRRVn1r ejzCv+Hzbva6DdaYnXC/itHRk/pt25LPeJwTB1ysMTTfKv67ffWvGDmriUKfdWMYNE1w UIjpMgwXYRCCweWlOIJjMVnTe45wVxZvTXA/jkmJJpyo2zCphSgUFpmJWWiGxZpJXd+Q IACdVF3Q9odaI4xCH1+ABUaQosEyj3gdAQTKoPViwlAVhFkJUgOrPwEo0VlqjdxhnANA OfxqMthc9nisU5kMlPtiyYMNiVKvw3qHWVd+rt5sbvt602HNpHTK5L4JBEPJgHAJsWXW ScHA== X-Gm-Message-State: AOJu0YynjYPf8EYHY8Yq9BTOSVUKfojGJAfZUOemhK6NBafXQlmKG/8E g0kn27xxx/j9OUZhDpCg/OcXu/3lar0= X-Google-Smtp-Source: AGHT+IGHbW+Ptdwzy92Kz+QYUaTmu72lqWDKNL7sbirXYuuiSg/ZwJ9LU+rrZG32uOTt1WvTB/WsDw== X-Received: by 2002:a17:906:3150:b0:9a1:f81f:d0d5 with SMTP id e16-20020a170906315000b009a1f81fd0d5mr23804043eje.54.1697266284068; Fri, 13 Oct 2023 23:51:24 -0700 (PDT) Received: from [192.168.1.10] ([95.43.220.235]) by smtp.googlemail.com with ESMTPSA id b8-20020a1709063f8800b00997e00e78e6sm540548ejj.112.2023.10.13.23.51.23 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 13 Oct 2023 23:51:23 -0700 (PDT) Subject: Re: [PATCH v2 2/3] pwm: bcm2835: allow pwm driver to be used in atomic context To: =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Alexander Stein Cc: Sean Young , linux-media@vger.kernel.org, Thierry Reding , Florian Fainelli , Ray Jui , Scott Branden , Broadcom internal kernel review list , Stefan Wahren , linux-pwm@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <6ce73b2688f059e7169935699044104cf37b2425.1697193646.git.sean@mess.org> <84429d39-aa54-462d-85cd-c5d06a614a0e@gmx.net> <5203415.ElGaqSPkdT@steina-w> <20231013175140.dzlz4grrgngoyxbc@pengutronix.de> From: Ivaylo Dimitrov Message-ID: Date: Sat, 14 Oct 2023 09:51:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20231013175140.dzlz4grrgngoyxbc@pengutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org On 13.10.23 г. 20:51 ч., Uwe Kleine-König wrote: > Hello, > > On Fri, Oct 13, 2023 at 01:13:50PM +0200, Alexander Stein wrote: >> Am Freitag, 13. Oktober 2023, 13:04:48 CEST schrieb Stefan Wahren: >>> Am 13.10.23 um 12:46 schrieb Sean Young: >>>> clk_get_rate() may do a mutex lock. Since the clock rate cannot change on >>>> an rpi, simply fetch it once. >>> >>> does it mean you checked all possible SoCs (BCM2835, BCM2836, BCM2837, >>> BCM2711, BCM2712) for this change? >>> >>> Is it impossible that the real clock can never be influenced by turbo >>> mode like SPI? >> >> Assuming the clock can change, which I would, then a clock notifier seems >> appropriate. See [1] for an example. > > I'm not a fan. If the clock changes, the output also changes. With a > clock notifier you can soften the issue and reconfigure to something > similar as the original wave form, but a glitch happens for sure. > Right, but without notifier, everything rate related after the change will be wrong Ivo