From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.fireflyinternet.com ([109.228.58.192]:63585 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751360AbeA3MBH (ORCPT ); Tue, 30 Jan 2018 07:01:07 -0500 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT To: Imre Deak , intel-gfx@lists.freedesktop.org From: Chris Wilson In-Reply-To: <20180130114712.2644-1-imre.deak@intel.com> Cc: =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= , stable@vger.kernel.org, #@vger.kernel.org, v4.4+@vger.kernel.org References: <20180130114712.2644-1-imre.deak@intel.com> Message-ID: <151731365868.10214.16293550615334319@mail.alporthouse.com> Subject: Re: [PATCH 1/3] drm/i915/bxt, glk: Increase PCODE timeouts during CDCLK freq changing Date: Tue, 30 Jan 2018 12:00:58 +0000 Sender: stable-owner@vger.kernel.org List-ID: Quoting Imre Deak (2018-01-30 11:47:10) > Currently we see sporadic timeouts during CDCLK changing both on BXT and > GLK as reported by the Bugzilla: ticket. It's easy to reproduce this by > changing the frequency in a tight loop after blanking the display. The > upper bound for the completion time is 800us based on my tests, so > increase it from the current 500us to 2ms; with that I couldn't trigger > the problem either on BXT or GLK. > > Note that timeouts happened during both the change notification and the > voltage level setting PCODE request. (For the latter one BSpec doesn't > require us to wait for completion before further HW programming.) > > This issue is similar to > 2c7d0602c815 ("drm/i915/gen9: Fix PCODE polling during CDCLK change > notification") > but there the PCODE request does complete (as shown by the mbox > busy flag), only the reply we get from PCODE indicates a failure. > So there we keep resending the request until a success reply, here we > just have to increase the timeout for the one PCODE request we send. > > Cc: Chris Wilson > Cc: Ville Syrjälä > Cc: stable@vger.kernel.org # v4.4+ > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103326 > Signed-off-by: Imre Deak Acked-by: Chris Wilson -Chris