Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755516AbbFCMMT (ORCPT ); Wed, 3 Jun 2015 08:12:19 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57460 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932641AbbFCMLT (ORCPT ); Wed, 3 Jun 2015 08:11:19 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable Cc: Greg Kroah-Hartman , Jean Delvare , Peter Feuerer Subject: [PATCH 3.14 52/64] thermal: step_wise: Revert optimization Date: Wed, 3 Jun 2015 20:43:20 +0900 Message-Id: <20150603063930.710988617@linuxfoundation.org> X-Mailer: git-send-email 2.4.2 In-Reply-To: <20150603063928.472620468@linuxfoundation.org> References: <20150603063928.472620468@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2028 Lines: 52 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jean Delvare Commit 178c2490b99f898efc06d1ad75cadc84f13021a6 ("thermal: step_wise: cdev only needs update on a new target state") broke driver acerhdf. That driver abused the step_wise thermal governor until the bang_bang governor was available, and the optimization broke this usage model. Kernels v3.12 to v3.18 are affected. In v3.19 the acerhdf driver was switched to the bang_bang governor and that solved the problem. For kernels v3.12 to v3.17, the bang_bang governor isn't available yet so the easiest fix is to revert the optimization. Signed-off-by: Jean Delvare Reported-by: Dieter Jurzitza (https://bugzilla.opensuse.org/show_bug.cgi?id=925961) Tested-by: Peter Feuerer Tested-by: Dieter Jurzitza --- Please consider this patch for stable kernel branches from v3.12 to v3.17. If anyone cares about v3.18, I think a better fix would be to backport commit 48c8dd64345ba2a8c41556095c7adacb1c8af7c1 ("acerhdf: Use bang-bang thermal governor") but it's too big for stable, so it's left to distributions. So maybe this fix should make it into v3.18 stable as well - I'll let whoever maintains that branch decide. drivers/thermal/step_wise.c | 3 --- 1 file changed, 3 deletions(-) --- a/drivers/thermal/step_wise.c +++ b/drivers/thermal/step_wise.c @@ -146,9 +146,6 @@ static void thermal_zone_trip_update(str dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", old_target, (int)instance->target); - if (old_target == instance->target) - continue; - /* Activate a passive thermal instance */ if (old_target == THERMAL_NO_TARGET && instance->target != THERMAL_NO_TARGET) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/