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 X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C68EDC433DB for ; Fri, 8 Jan 2021 14:33:59 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 7429F235FC for ; Fri, 8 Jan 2021 14:33:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7429F235FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 088816E187; Fri, 8 Jan 2021 14:33:59 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9FCD16E187 for ; Fri, 8 Jan 2021 14:33:57 +0000 (UTC) IronPort-SDR: 6Tcd0BhgKK3OkSGQEzUooPxrI6/G54cpVFcsGizmM/5M8oHus9pb8eMaZtdUmCIykwCIzyKB7i HWdUfDELAJNg== X-IronPort-AV: E=McAfee;i="6000,8403,9857"; a="177700672" X-IronPort-AV: E=Sophos;i="5.79,331,1602572400"; d="scan'208";a="177700672" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2021 06:33:56 -0800 IronPort-SDR: ruw+Y3QMjN/aEGAFlWuk045dPXwcJU1aWCVj9MUmusqkRhB7FOykSvHtOfTFGaWxVzKJRa43Ni QVdelrTeIYbw== X-IronPort-AV: E=Sophos;i="5.79,331,1602572400"; d="scan'208";a="380137472" Received: from ideak-desk.fi.intel.com ([10.237.68.141]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jan 2021 06:33:55 -0800 Date: Fri, 8 Jan 2021 16:33:51 +0200 From: Imre Deak To: Jani Nikula Message-ID: <20210108143351.GA233313@ideak-desk.fi.intel.com> References: <20210107112500.16216-1-anshuman.gupta@intel.com> <87ft3bzs3n.fsf@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87ft3bzs3n.fsf@intel.com> Subject: Re: [Intel-gfx] [PATCH] drm/i915/pps: Reuse POWER_DOMAIN_DISPLAY_CORE in pps_{lock, unlock} 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Jan 08, 2021 at 11:38:04AM +0200, Jani Nikula wrote: > On Thu, 07 Jan 2021, Anshuman Gupta wrote: > > We need a power_domain wakeref in pps_{lock,unlock} to prevent > > a race while resetting pps state in intel_power_sequencer_reset(). > > > > intel_power_sequencer_reset() need a pps_mutex to access pps_pipe > > but it can't grab pps_mutex due to deadlock with power_well > > functions are called while holding pps_mutex. > > intel_power_sequencer_reset() is called by power_well function > > associated with legacy platforms like vlv and chv therefore re-use > > the POWER_DOMAIN_DISPLAY_CORE power domain, which only used > > by vlv and chv display power domain. > > > > This will avoids the unnecessary noise of unrelated power wells > > in pps_{lock,unlock}. > > > > Cc: Jani Nikula > > Cc: Imre Deak > > Signed-off-by: Anshuman Gupta > > Imre convinced me yesterday on irc that this should work. > > Reviewed-by: Jani Nikula > > On the surface, this reduces the need to enable/disable the aux power so > much. It's unnecessary, so it stands to reason to optimize it. We should > only grab the domain references we actually need. > > However, this *also* papers over an issue we've been seeing [1]. We need > to be aware the root cause for that remains unknown, and needs to be > figured out. > > I presume simply doing aux transfers won't reproduce the problem, > because that disables the power asynchronously since commit f39194a7a8b9 > ("drm/i915: Disable power asynchronously during DP AUX > transfers"). Perhaps we wouldn't have seen this at all if pps_unlock() > also did that as suggested in the commit message. > > Anyway, I'd like to get acks or rb's from Imre and Ville before merging > this. Looks ok to me: Acked-by: Imre Deak > > > BR, > Jani. > > > [1] http://lore.kernel.org/r/20201204081845.26528-1-anshuman.gupta@intel.com > > > > --- > > drivers/gpu/drm/i915/display/intel_dp.c | 8 ++------ > > 1 file changed, 2 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c > > index 8a00e609085f..4f190a82d4ad 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > > @@ -895,9 +895,7 @@ pps_lock(struct intel_dp *intel_dp) > > * See intel_power_sequencer_reset() why we need > > * a power domain reference here. > > */ > > - wakeref = intel_display_power_get(dev_priv, > > - intel_aux_power_domain(dp_to_dig_port(intel_dp))); > > - > > + wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_DISPLAY_CORE); > > mutex_lock(&dev_priv->pps_mutex); > > > > return wakeref; > > @@ -909,9 +907,7 @@ pps_unlock(struct intel_dp *intel_dp, intel_wakeref_t wakeref) > > struct drm_i915_private *dev_priv = dp_to_i915(intel_dp); > > > > mutex_unlock(&dev_priv->pps_mutex); > > - intel_display_power_put(dev_priv, > > - intel_aux_power_domain(dp_to_dig_port(intel_dp)), > > - wakeref); > > + intel_display_power_put(dev_priv, POWER_DOMAIN_DISPLAY_CORE, wakeref); > > return 0; > > } > > -- > Jani Nikula, Intel Open Source Graphics Center _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx