From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6834FC3DA6E for ; Fri, 5 Jan 2024 13:38:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D64C910E5E2; Fri, 5 Jan 2024 13:38:33 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.93]) by gabe.freedesktop.org (Postfix) with ESMTPS id C366610E5E2 for ; Fri, 5 Jan 2024 13:38:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1704461912; x=1735997912; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:content-transfer-encoding:in-reply-to; bh=Oz7Zp2MmxhY7KloMcuoTsn+jV+Ok9059CrbUS85+lbQ=; b=ScyBpix+VjmbVd8aeRdQotfHs1bxb21pN1z4b0LNjf2O4C+Z06tDMpi/ DxEXdKx3I+Aq9XDwkA/b49wK+tLYMOLBGxvkGaLEy3anJOYa+S0CRpdkL URjr6koEHKgsoL11y4swyRSPsIkIL2kBki8gkIwQu2CfIWZCbUIEfE2NN aRvDpXbxvQNImSudeSgl9N67+DQbOitbkN2HCmmqKbyod4+jnSmj5IyTp uJt2RpOQLLIMrCn0KHpKAq52qnegLaSVqjkN4HJd+EJ4DGRbmpp7Ms5nj DGtfEA+gQNvvV8HRZWt/dDKmA8CD79YIny/OOVm/eaqj+9NPVAWbVubQp g==; X-IronPort-AV: E=McAfee;i="6600,9927,10944"; a="394680128" X-IronPort-AV: E=Sophos;i="6.04,333,1695711600"; d="scan'208";a="394680128" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jan 2024 05:38:32 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10944"; a="851138032" X-IronPort-AV: E=Sophos;i="6.04,333,1695711600"; d="scan'208";a="851138032" Received: from ideak-desk.fi.intel.com ([10.237.72.78]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jan 2024 05:38:31 -0800 Date: Fri, 5 Jan 2024 15:38:42 +0200 From: Imre Deak To: "Hogander, Jouni" Subject: Re: [PATCH 02/12] drm/i915: Keep the connector polled state disabled after storm Message-ID: References: <20240104083008.2715733-1-imre.deak@intel.com> <20240104083008.2715733-3-imre.deak@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: imre.deak@intel.com Cc: "intel-gfx@lists.freedesktop.org" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Jan 05, 2024 at 03:23:49PM +0200, Hogander, Jouni wrote: > On Thu, 2024-01-04 at 10:29 +0200, Imre Deak wrote: > > If an HPD IRQ storm is detected on a connector during driver loading or > > system suspend/resume - disabling the IRQ and switching to polling - the > > polling may get disabled too early - before the intended 2 minute > > HPD_STORM_REENABLE_DELAY - with the HPD IRQ staying disabled for this > > duration. One such sequence is: > > > > Thread#1 Thread#2 > > intel_display_driver_probe()-> > > intel_hpd_init()-> > > (HPD IRQ gets enabled) > > . intel_hpd_irq_handler()-> > > . intel_hpd_irq_storm_detect() > > . intel_hpd_irq_setup()-> > > . (HPD IRQ gets disabled) > > . queue_delayed_work(hotplug.hotplug_work) > > . ... > > . i915_hotplug_work_func()-> > > . intel_hpd_irq_storm_switch_to_polling()-> > > . (polling enabled) > > . > > intel_hpd_poll_disable()-> > > queue_work(hotplug.poll_init_work) > > ... > > i915_hpd_poll_init_work()-> > > (polling gets disabled, > > HPD IRQ is still disabled) > > ... > > > > (Connector is neither polled or > > detected via HPD IRQs for 2 minutes) > > > > intel_hpd_irq_storm_reenable_work()-> > > (HPD IRQ gets enabled) > > > > To avoid the above 2 minute state without either polling or enabled HPD > > IRQ, leave the connector's polling mode unchanged in > > i915_hpd_poll_init_work() if its HPD IRQ got disabled after an IRQ storm > > indicated by the connector's HPD_DISABLED pin state. > > Is it actually order which needs to be ensured here? I.e. ensure that > polling is disabled before hpd interrupt gets enabled? Disabling the polling also means that there is an explicit detection of the connectors. This explicit detection at boot-up and resume must happen _after_ the HPD interrupts are enabled, otherwise you could miss an HPD connect/disconnect interrupt and leave the connector in a stale connected state. > Why disabling polling is queued work and not just done during init/resume? To reduce the latency of boot-up and resume. > BR, > > Jouni Högander > > > > > Signed-off-by: Imre Deak > > --- > > drivers/gpu/drm/i915/display/intel_hotplug.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c > > b/drivers/gpu/drm/i915/display/intel_hotplug.c > > index 0c0700c6ec66d..74513c3d3690b 100644 > > --- a/drivers/gpu/drm/i915/display/intel_hotplug.c > > +++ b/drivers/gpu/drm/i915/display/intel_hotplug.c > > @@ -710,6 +710,8 @@ static void i915_hpd_poll_init_work(struct > > work_struct *work) > > cancel_work(&dev_priv- > > >display.hotplug.poll_init_work); > > } > > > > + spin_lock_irq(&dev_priv->irq_lock); > > + > > drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter); > > for_each_intel_connector_iter(connector, &conn_iter) { > > enum hpd_pin pin; > > @@ -718,6 +720,9 @@ static void i915_hpd_poll_init_work(struct > > work_struct *work) > > if (pin == HPD_NONE) > > continue; > > > > + if (dev_priv->display.hotplug.stats[pin].state == > > HPD_DISABLED) > > + continue; > > + > > connector->base.polled = connector->polled; > > > > if (enabled && connector->base.polled == > > DRM_CONNECTOR_POLL_HPD) > > @@ -726,6 +731,8 @@ static void i915_hpd_poll_init_work(struct > > work_struct *work) > > } > > drm_connector_list_iter_end(&conn_iter); > > > > + spin_unlock_irq(&dev_priv->irq_lock); > > + > > if (enabled) > > drm_kms_helper_poll_reschedule(&dev_priv->drm); > > >