From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761939AbdAEKmT (ORCPT ); Thu, 5 Jan 2017 05:42:19 -0500 Received: from fllnx209.ext.ti.com ([198.47.19.16]:43007 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752273AbdAEKlS (ORCPT ); Thu, 5 Jan 2017 05:41:18 -0500 Subject: Re: [PATCH] drm: Schedule the output_poll_work with 1s delay if we have delayed event To: , , , , , , , References: <20170104120053.31882-1-peter.ujfalusi@ti.com> <20170105084324.n33j6jrprnhbg736@phenom.ffwll.local> From: Peter Ujfalusi Message-ID: <1d7bbe7d-428e-5ad6-4bea-70bad4e62f3f@ti.com> Date: Thu, 5 Jan 2017 12:40:29 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20170105084324.n33j6jrprnhbg736@phenom.ffwll.local> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/05/2017 10:43 AM, Daniel Vetter wrote: > On Wed, Jan 04, 2017 at 02:00:53PM +0200, Peter Ujfalusi wrote: >> Instead of scheduling the work to handle the initial delayed event, use 1s >> delay. >> >> When the delayed event is handled w/o delay - in a similar matter when the >> poll had been initialized before drm_helper_probe_single_connector_modes() >> is called - it triggers a race in Optimus setups. >> >> Fixes: 339fd36238dd ("drm: drm_probe_helper: Fix output_poll_work scheduling") >> Cc: stable@vger.kernel.org # v4.9 >> Signed-off-by: Peter Ujfalusi >> --- >> Hi, >> >> related bug report: https://bugs.freedesktop.org/show_bug.cgi?id=98690 >> >> Regards, >> Peter >> >> drivers/gpu/drm/drm_probe_helper.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c >> index 98ed110e28ed..f30c14b0a72f 100644 >> --- a/drivers/gpu/drm/drm_probe_helper.c >> +++ b/drivers/gpu/drm/drm_probe_helper.c >> @@ -146,8 +146,9 @@ void drm_kms_helper_poll_enable_locked(struct drm_device *dev) >> drm_connector_list_iter_put(&conn_iter); >> >> if (dev->mode_config.delayed_event) { >> + /* Use short (1s) delay to handle the initial delayed event */ >> poll = true; >> - delay = 0; >> + delay = HZ; > > This smells a bit like duct-tape papering over some other race. Yes, I agree. We could revert 339fd36238dd also to put back the duct-tape. > Lack of > locking or something else. Most likely some drivers enable polling a bit > too early in their load sequence. All is pointing to Optimus. Intel and nouveau alone works, but we have failure on Optimus laptops. I have tried to narrow it down with another patch attached to the bugzilla: https://bugs.freedesktop.org/attachment.cgi?id=128742 I expected it to fix the problem. But it did not. So I'm puzzled. >And if we can't figure this out, then we > need some really big FIXME: here that this papers over driver races. Yeah, now we know that there is something wrong in some driver(s). We can hide it with delaying the poll_work. It would be great if nouveau/optimus guys would be able to take a look at this. > -Daniel > >> } >> >> if (poll) >> -- >> 2.11.0 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > -- Péter