From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH] ARM: tegra: Fix suspend hang on Tegra124 Chromebooks Date: Mon, 21 Dec 2015 09:50:08 +0000 Message-ID: <5677CB50.7030907@nvidia.com> References: <1449570409-30244-1-git-send-email-jonathanh@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1449570409-30244-1-git-send-email-jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: Stephen Warren , Alexandre Courbot , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org Ping? On 08/12/15 10:26, Jon Hunter wrote: > 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>; > }; > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html