From patchwork Thu Feb 27 22:26:49 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paulo Zanoni X-Patchwork-Id: 3736561 Return-Path: X-Original-To: patchwork-intel-gfx@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 B219EBF13A for ; Thu, 27 Feb 2014 22:27:59 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id AFEA52021B for ; Thu, 27 Feb 2014 22:27:58 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 9A4222011E for ; Thu, 27 Feb 2014 22:27:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EB9181058DF; Thu, 27 Feb 2014 14:27:44 -0800 (PST) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mail-yk0-f174.google.com (mail-yk0-f174.google.com [209.85.160.174]) by gabe.freedesktop.org (Postfix) with ESMTP id 036891058DB for ; Thu, 27 Feb 2014 14:27:39 -0800 (PST) Received: by mail-yk0-f174.google.com with SMTP id 20so8460322yks.5 for ; Thu, 27 Feb 2014 14:27:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=U4TJPV4vZb6p8h/Fm1n8p1a35BBVp1JX42wcIM3Hzhw=; b=OsO6JcbUD3Z5HisapU6QcD8VrQtK7z9mmyz94iAMUXNQ/bkkOSTRWL5CPk/CsVjUKG bilfBhAj+HMR3iOV+tnmBGQ/NgayqYPW9/iR/k0QpE7dQ+Mf1O9gT23eJ48SU2h0evWt fUbtw4gjHhSLgGdQK0W1xtqpTJbPE0Xdddmt8XnaXnKlAWQTROBsSX5PyndhCi+4A1EU ekZjh7LjB6WEMd/2us37L7ujAsntOf7n2tYfNAiEapS20BUvRMAj+0i+mtd9LpHW5hkH VbBbRD1yLL+UyWp2wvutww79GVGFhn+SrYU08YB8MkfW6x13NQVVjWhII0STLNJN6Hy1 IZNw== X-Received: by 10.236.82.226 with SMTP id o62mr17738227yhe.90.1393540059681; Thu, 27 Feb 2014 14:27:39 -0800 (PST) Received: from localhost.localdomain ([177.132.50.39]) by mx.google.com with ESMTPSA id t58sm18099538yho.20.2014.02.27.14.27.38 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Feb 2014 14:27:39 -0800 (PST) From: Paulo Zanoni To: intel-gfx@lists.freedesktop.org Date: Thu, 27 Feb 2014 19:26:49 -0300 Message-Id: <1393540010-1582-23-git-send-email-przanoni@gmail.com> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1393540010-1582-1-git-send-email-przanoni@gmail.com> References: <1393540010-1582-1-git-send-email-przanoni@gmail.com> Cc: Paulo Zanoni Subject: [Intel-gfx] [PATCH 22/23] drm/i915: update the PC8 and runtime PM documentation X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: intel-gfx-bounces@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org X-Spam-Status: No, score=-4.1 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, T_DKIM_INVALID, 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 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. Signed-off-by: Paulo Zanoni --- 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 08b22e3..a7aeb38 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1297,47 +1297,19 @@ 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 frmo 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 @@ -1347,7 +1319,7 @@ 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 c981e63..4354946 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -6651,6 +6651,29 @@ static void hsw_restore_lcpll(struct drm_i915_private *dev_priv) gen6_gt_force_wake_put_no_rpm(dev_priv, FORCEWAKE_ALL); } +/* + * 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;