From patchwork Tue Oct 21 10:51:31 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dheeraj Jamwal X-Patchwork-Id: 5118061 Return-Path: X-Original-To: patchwork-ltsi-dev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id B5952C11AC for ; Tue, 21 Oct 2014 11:38:38 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B0EED2010F for ; Tue, 21 Oct 2014 11:38:37 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 913BB20107 for ; Tue, 21 Oct 2014 11:38:36 +0000 (UTC) Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 9CB18FD1; Tue, 21 Oct 2014 11:06:48 +0000 (UTC) X-Original-To: ltsi-dev@lists.linuxfoundation.org Delivered-To: ltsi-dev@mail.linuxfoundation.org Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 466F1C54 for ; Tue, 21 Oct 2014 11:06:47 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 897B31FA0F for ; Tue, 21 Oct 2014 11:06:46 +0000 (UTC) Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP; 21 Oct 2014 04:06:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,761,1406617200"; d="scan'208";a="617796623" Received: from ubuntu-desktop.png.intel.com ([10.221.122.25]) by fmsmga002.fm.intel.com with ESMTP; 21 Oct 2014 04:06:40 -0700 From: Dheeraj Jamwal To: ltsi-dev@lists.linuxfoundation.org Date: Tue, 21 Oct 2014 18:51:31 +0800 Message-Id: <1413889294-31328-492-git-send-email-dheerajx.s.jamwal@intel.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1413889294-31328-1-git-send-email-dheerajx.s.jamwal@intel.com> References: <1413889294-31328-1-git-send-email-dheerajx.s.jamwal@intel.com> X-Spam-Status: No, score=-5.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, 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 Subject: [LTSI-dev] [PATCH 0491/1094] drm/i915: update the PC8 and runtime PM documentation X-BeenThere: ltsi-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: "A list to discuss patches, development, and other things related to the LTSI project" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ltsi-dev-bounces@lists.linuxfoundation.org Errors-To: ltsi-dev-bounces@lists.linuxfoundation.org X-Virus-Scanned: ClamAV using ClamSMTP From: Paulo Zanoni Now that PC8 got much simpler, there are less things to document. Also, runtime PM already has a nice documentation, so we don't need to re-explain it on our driver. v2: - Rebase. - Fix typo (Jesse). Reviewed-by: Jesse Barnes Signed-off-by: Paulo Zanoni Signed-off-by: Daniel Vetter (cherry picked from commit 765dab67528ac2490d8a9f68d05cc678861584d6) Signed-off-by: Dheeraj Jamwal --- drivers/gpu/drm/i915/i915_drv.h | 52 ++++++++-------------------------- drivers/gpu/drm/i915/intel_display.c | 23 +++++++++++++++ 2 files changed, 35 insertions(+), 40 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 20db5d8..9cd870f 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1337,47 +1337,19 @@ struct ilk_wm_values { }; /* - * This struct tracks the state needed for the Package C8+ feature. + * This struct helps tracking the state needed for runtime PM, which puts the + * device in PCI D3 state. Notice that when this happens, nothing on the + * graphics device works, even register access, so we don't get interrupts nor + * anything else. * - * TODO: we're merging the Package C8+ feature with the runtime PM support. To - * avoid having to update the documentation at each patch of the series, we'll - * do a final update at the end. + * Every piece of our code that needs to actually touch the hardware needs to + * either call intel_runtime_pm_get or call intel_display_power_get with the + * appropriate power domain. * - * Package states C8 and deeper are really deep PC states that can only be - * reached when all the devices on the system allow it, so even if the graphics - * device allows PC8+, it doesn't mean the system will actually get to these - * states. - * - * Our driver only allows PC8+ when all the outputs are disabled, the power well - * is disabled and the GPU is idle. When these conditions are met, we manually - * do the other conditions: disable the interrupts, clocks and switch LCPLL - * refclk to Fclk. - * - * When we really reach PC8 or deeper states (not just when we allow it) we lose - * the state of some registers, so when we come back from PC8+ we need to - * restore this state. We don't get into PC8+ if we're not in RC6, so we don't - * need to take care of the registers kept by RC6. - * - * The interrupt disabling is part of the requirements. We can only leave the - * PCH HPD interrupts enabled. If we're in PC8+ and we get another interrupt we - * can lock the machine. - * - * Ideally every piece of our code that needs PC8+ disabled would call - * hsw_disable_package_c8, which would increment disable_count and prevent the - * system from reaching PC8+. But we don't have a symmetric way to do this for - * everything, so we have the requirements_met variable. When we switch - * requirements_met to true we decrease disable_count, and increase it in the - * opposite case. The requirements_met variable is true when all the CRTCs, - * encoders and the power well are disabled. - * - * In addition to everything, we only actually enable PC8+ if disable_count - * stays at zero for at least some seconds. This is implemented with the - * enable_work variable. We do this so we don't enable/disable PC8 dozens of - * consecutive times when all screens are disabled and some background app - * queries the state of our connectors, or we have some application constantly - * waking up to use the GPU. Only after the enable_work function actually - * enables PC8+ the "enable" variable will become true, which means that it can - * be false even if disable_count is 0. + * Our driver uses the autosuspend delay feature, which means we'll only really + * suspend if we stay with zero refcount for a certain amount of time. The + * default value is currently very conservative (see intel_init_runtime_pm), but + * it can be changed with the standard runtime PM files from sysfs. * * The irqs_disabled variable becomes true exactly after we disable the IRQs and * goes back to false exactly before we reenable the IRQs. We use this variable @@ -1387,7 +1359,7 @@ struct ilk_wm_values { * inside struct regsave so when we restore the IRQs they will contain the * latest expected values. * - * For more, read "Display Sequences for Package C8" on our documentation. + * For more, read the Documentation/power/runtime_pm.txt. */ struct i915_runtime_pm { bool suspended; diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 3648ed6..e54e77d 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -7022,6 +7022,29 @@ static void hsw_restore_lcpll(struct drm_i915_private *dev_priv) spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); } +/* + * Package states C8 and deeper are really deep PC states that can only be + * reached when all the devices on the system allow it, so even if the graphics + * device allows PC8+, it doesn't mean the system will actually get to these + * states. Our driver only allows PC8+ when going into runtime PM. + * + * The requirements for PC8+ are that all the outputs are disabled, the power + * well is disabled and most interrupts are disabled, and these are also + * requirements for runtime PM. When these conditions are met, we manually do + * the other conditions: disable the interrupts, clocks and switch LCPLL refclk + * to Fclk. If we're in PC8+ and we get an non-hotplug interrupt, we can hard + * hang the machine. + * + * When we really reach PC8 or deeper states (not just when we allow it) we lose + * the state of some registers, so when we come back from PC8+ we need to + * restore this state. We don't get into PC8+ if we're not in RC6, so we don't + * need to take care of the registers kept by RC6. Notice that this happens even + * if we don't put the device in PCI D3 state (which is what currently happens + * because of the runtime PM support). + * + * For more, read "Display Sequences for Package C8" on the hardware + * documentation. + */ void hsw_enable_pc8(struct drm_i915_private *dev_priv) { struct drm_device *dev = dev_priv->dev;