From patchwork Thu Dec 26 19:12:24 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Blumenstingl X-Patchwork-Id: 11310693 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 59522138D for ; Thu, 26 Dec 2019 19:13:17 +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 333EB206CB for ; Thu, 26 Dec 2019 19:13:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Vh8Bw15O"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=googlemail.com header.i=@googlemail.com header.b="klF/ucA9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 333EB206CB Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=googlemail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-amlogic-bounces+patchwork-linux-amlogic=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:References:In-Reply-To: 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: List-Owner; bh=uwzGynKRppreUXiT8+vJ4fsDYZCfOuwBrr0Z/513F5I=; b=Vh8Bw15O4VyR5Y iXaBZ2W5Fe2SsKfQnWSNI7amiiai6Y3jkMcR0SZDNJZssU/UdG4UUUiCroigfaGIM8PI+5bBDf38K grm9WEPppAOVuRMBfGCeG+2o8Kj51kPhvmfR+ZoA6LiZPH9WiP054z/sBiorBBkZlLOXmc9wvwidB TTIKBC6lGYwGazS8FBRo+jYpkANAlOzXB/kb6cIdAOybXkeJA4x1sS9Pa3fKYmFfKSQZjJNZZRtrK 9si54q+Uqk7YDUdXOARlwtYiVBNiS7M2Wr3xY8BMaDMEF1ppPd9xJRshAVk5p2ED19QNIu82C9cFx WJsi/OMXFKyDkn2cmBYg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ikYZQ-00024k-7i; Thu, 26 Dec 2019 19:13:16 +0000 Received: from mail-wr1-x441.google.com ([2a00:1450:4864:20::441]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ikYYw-0001Wl-OK; Thu, 26 Dec 2019 19:12:48 +0000 Received: by mail-wr1-x441.google.com with SMTP id w15so11719416wru.4; Thu, 26 Dec 2019 11:12:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=mmT0zF9OrkbiD8lj/0dOwJG0ayj5vgSHBwzc+nFQ5Gg=; b=klF/ucA9NSUXwoHRk1+Si9sfnX9CSLC+s/ebG98azsGLVJj1eJB4Gh6K3XoDxFlgwf e4nZ54SihxAA0YFfk6F238dYP9TkFDlIdBWYh29QftbkX6XICz13muXv7qfEFCaUuUQp CoschbCdrD2XhSLd6SH9cxWtcrwocY4bonRfJDgF/CSuyvksP5uvGZLJz34FGSHXsrYg zsLYDYhhxGFxKmdmRKvL1TWzEJnbemd/PDUm2ivSnrRB7Y9/J1HMeXM/nofk/edIPYUi LHC/Mn0XfMUpeWAegjzOMgII4GO2Y5c/8pyPTtVL95QBAq4GwW17CZ6pacVbQsAwGKv0 faqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=mmT0zF9OrkbiD8lj/0dOwJG0ayj5vgSHBwzc+nFQ5Gg=; b=S3JvuBZzA61qfpgP8S4cWdfppggw8K1bbJte/IHQaJTuuCQ27/nbZO5Kd9lGtRUTRW JTNKE8JSWKNg9SM4/1eThlhCcteN/l/7+iKRKV7NMSg6r3h4ijBA46EaX1SJyxD/Ty+u QCDfeP1B8nIaOMP7edENk7OPRNX/r9Ss4XgJJeNtr7E2AScDDt33Hk/H1EfxRr3ObwKV nTMrx+vgiYdhAJd9+WRwn1EDFHZiMnEHsoqyWjsW5sxUoOKTNB09/HqCYm3C8aAokRCl xNkPvPK+ODSsnF3pHwtFQAXQdt6ehlOaMX/tb011iOTniozAjtz7i2Ta9KmVIttjHcgG 5PVg== X-Gm-Message-State: APjAAAV1oiWStr6oc9DKG09fEuaXIOgsWcsjQGasNwEJkuwNOxyHd1VL sv0M2RJJyIiwRyOCmwcTJVuzdX2kQM0= X-Google-Smtp-Source: APXvYqzFEhUhoMbvJ+dMFP1fHZY7u43hjf0Ydx1AtPN8kQZ0UFLEecCP0onL5y0FIk42usYSrzPz3A== X-Received: by 2002:a5d:4085:: with SMTP id o5mr45964730wrp.321.1577387565138; Thu, 26 Dec 2019 11:12:45 -0800 (PST) Received: from localhost.localdomain (p200300F1373A1900428D5CFFFEB99DB8.dip0.t-ipconnect.de. [2003:f1:373a:1900:428d:5cff:feb9:9db8]) by smtp.googlemail.com with ESMTPSA id o7sm8965937wmh.11.2019.12.26.11.12.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Dec 2019 11:12:44 -0800 (PST) From: Martin Blumenstingl To: linux-amlogic@lists.infradead.org, jbrunet@baylibre.com, sboyd@kernel.org Subject: [PATCH v2 2/2] clk: clarify that clk_set_rate() does updates from top to bottom Date: Thu, 26 Dec 2019 20:12:24 +0100 Message-Id: <20191226191224.3785282-3-martin.blumenstingl@googlemail.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191226191224.3785282-1-martin.blumenstingl@googlemail.com> References: <20191226191224.3785282-1-martin.blumenstingl@googlemail.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191226_111246_789911_F5C55CB4 X-CRM114-Status: GOOD ( 12.41 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:441 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (martin.blumenstingl[at]googlemail.com) -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_VALID Message has at least one valid DKIM or DK signature 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 X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: narmstrong@baylibre.com, Martin Blumenstingl , mturquette@baylibre.com, linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+patchwork-linux-amlogic=patchwork.kernel.org@lists.infradead.org clk_set_rate() currently starts updating the rate for a clock at the top-most affected clock and then walks down the tree to update the bottom-most affected clock last. This behavior is important for protected clocks where we can switch between multiple parents to achieve the same output. An example for this is the mali clock tree on Amlogic SoCs: mali_0_mux (must not change when enabled) mali_0_div (must not change when enabled) mali_0 (gate) mali_1_mux (must not change when enabled) mali_1_div (must not change when enabled) mali_1 (gate) The final output can either use mali_0_gate or mali_1. To change the final output we must switch to the "inactive" tree. Assuming mali_0 is active, then we need to prepare mali_1 with the new desired rate and finally switch the output to the mali_1 tree. This process will then protect the mali_1 tree and at the same time unprotect the mali_0 tree. The next call to clk_set_rate() will then switch from the mali_1 tree back to mali_0. Signed-off-by: Martin Blumenstingl Acked-by: Stephen Boyd --- include/linux/clk.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/linux/clk.h b/include/linux/clk.h index 18b7b95a8253..7fd6a1febcf4 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -627,6 +627,9 @@ long clk_round_rate(struct clk *clk, unsigned long rate); * @clk: clock source * @rate: desired clock rate in Hz * + * Updating the rate starts at the top-most affected clock and then + * walks the tree down to the bottom-most clock that needs updating. + * * Returns success (0) or negative errno. */ int clk_set_rate(struct clk *clk, unsigned long rate);