From patchwork Tue Dec 8 10:26:49 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jon Hunter X-Patchwork-Id: 7796321 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id BCA049F39B for ; Tue, 8 Dec 2015 10:29:10 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D251C20490 for ; Tue, 8 Dec 2015 10:29:09 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D2FCD2047C for ; Tue, 8 Dec 2015 10:29:08 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a6FUU-00040V-Ri; Tue, 08 Dec 2015 10:27:26 +0000 Received: from hqemgate14.nvidia.com ([216.228.121.143]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a6FUN-0003gh-1c for linux-arm-kernel@lists.infradead.org; Tue, 08 Dec 2015 10:27:21 +0000 Received: from hqnvupgp08.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com id ; Tue, 08 Dec 2015 02:27:13 -0800 Received: from hqemhub02.nvidia.com ([172.20.150.31]) by hqnvupgp08.nvidia.com (PGP Universal service); Tue, 08 Dec 2015 02:23:45 -0800 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Tue, 08 Dec 2015 02:23:45 -0800 Received: from jonathanh-lm.nvidia.com (172.20.144.16) by hqemhub02.nvidia.com (172.20.150.31) with Microsoft SMTP Server (TLS) id 8.3.406.0; Tue, 8 Dec 2015 02:26:57 -0800 From: Jon Hunter To: Stephen Warren , Thierry Reding , Alexandre Courbot , linux-arm-kernel@lists.infradead.org Subject: [PATCH] ARM: tegra: Fix suspend hang on Tegra124 Chromebooks Date: Tue, 8 Dec 2015 10:26:49 +0000 Message-ID: <1449570409-30244-1-git-send-email-jonathanh@nvidia.com> X-Mailer: git-send-email 2.1.4 X-NVConfidentiality: public MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151208_022719_488222_D2D1E457 X-CRM114-Status: GOOD ( 15.01 ) X-Spam-Score: -6.9 (------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-tegra@vger.kernel.org, devicetree@vger.kernel.org, Jon Hunter Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Enabling CPUFreq support for Tegra124 Chromebooks is causing the Tegra124 to hang when resuming from suspend. When CPUFreq is enabled, the CPU clock is changed from the PLLX clock to the DFLL clock during kernel boot. When resuming from suspend the CPU clock is temporarily changed back to the PLLX clock before switching back to the DFLL. If the DFLL is operating at a much lower frequency than the PLLX when we enter suspend, and so the CPU voltage rail is at a voltage too low for the CPUs to operate at the PLLX frequency, then the device will hang. Please note that the PLLX is used in the resume sequence to switch the CPU clock from the very slow 32K clock to a faster clock during early resume to speed up the resume sequence before the DFLL is resumed. Ideally, we should fix this by setting the suspend frequency so that it matches the PLLX frequency, however, that would be a bigger change. For now simply disable CPUFreq support for Tegra124 Chromebooks to avoid the hang when resuming from suspend. Fixes: 9a0baee960a7 ("ARM: tegra: Enable CPUFreq support for Tegra124 Chromebooks") Signed-off-by: Jon Hunter --- Please note that this fix is required for v4.4 arch/arm/boot/dts/tegra124-nyan.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/tegra124-nyan.dtsi b/arch/arm/boot/dts/tegra124-nyan.dtsi index 40c23a0b7cfc..ec1aa64ded68 100644 --- a/arch/arm/boot/dts/tegra124-nyan.dtsi +++ b/arch/arm/boot/dts/tegra124-nyan.dtsi @@ -399,7 +399,7 @@ /* CPU DFLL clock */ clock@0,70110000 { - status = "okay"; + status = "disabled"; vdd-cpu-supply = <&vdd_cpu>; nvidia,i2c-fs-rate = <400000>; };