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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 73D21C433DB for ; Fri, 19 Mar 2021 21:20:16 +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 0287661934 for ; Fri, 19 Mar 2021 21:20:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0287661934 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 67CBF6EACC; Fri, 19 Mar 2021 21:20:15 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 20A3C6EACF; Fri, 19 Mar 2021 21:20:14 +0000 (UTC) IronPort-SDR: eGySvO/9JMWf3eYSW86K1VhDXWPviWfOA4OATka1Ogmca/VulA50omBAxrV4FzqCtHeqFvQEX8 4suAAXOVffig== X-IronPort-AV: E=McAfee;i="6000,8403,9928"; a="189349951" X-IronPort-AV: E=Sophos;i="5.81,262,1610438400"; d="scan'208";a="189349951" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2021 14:20:13 -0700 IronPort-SDR: BntxX2HNWbdlg4tlKXJuz3IGOFO0T7TwJxy+Uz7VVmBiLxv8ZDqi1w9i46RRm40bmos9lX0uDe BXUOICqmvuow== X-IronPort-AV: E=Sophos;i="5.81,262,1610438400"; d="scan'208";a="406948661" Received: from labuser-z97x-ud5h.jf.intel.com (HELO labuser-Z97X-UD5H) ([10.165.21.211]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2021 14:20:13 -0700 Date: Fri, 19 Mar 2021 14:26:24 -0700 From: "Navare, Manasi" To: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Message-ID: <20210319212624.GA6560@labuser-Z97X-UD5H> References: <20210303104744.2c064f09@eldfell> <20210303204433.GA15819@labuser-Z97X-UD5H> <20210304104223.6b3490bc@eldfell> <20210309005252.GA27491@labuser-Z97X-UD5H> <20210309111350.3be0543f@eldfell> <20210318230126.GA1900@labuser-Z97X-UD5H> <20210319205413.GA6359@labuser-Z97X-UD5H> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Subject: Re: [Intel-gfx] [PATCH] drm/atomic: Add the crtc to affected crtc only if uapi.enable = true 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: , Cc: Daniel Vetter , intel-gfx , dri-devel , Daniel Stone Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Mar 19, 2021 at 11:12:41PM +0200, Ville Syrj=E4l=E4 wrote: > On Fri, Mar 19, 2021 at 01:54:13PM -0700, Navare, Manasi wrote: > > On Fri, Mar 19, 2021 at 04:56:24PM +0200, Ville Syrj=E4l=E4 wrote: > > > On Thu, Mar 18, 2021 at 04:01:26PM -0700, Navare, Manasi wrote: > > > > So basically we see this warning only in case of bigjoiner when > > > > drm_atomic_check gets called without setting the state->allow_modes= et flag. > > > = > > > Considering the code is 'WARN(!state->allow_modeset, ...' that > > > fact should be rather obvious. > > > = > > > > = > > > > So do you think that in i915, in intel_atomic_check_bigjoiner() we = should only > > > > steal the crtc when allow_modeset flag is set in state? > > > = > > > No. If you fully read drm_atomic_check_only() you will observe > > > that it will reject any commit w/ allow_modeset=3D=3Dfalse which = > > > needs a modeset. And it does that before the WARN. > > > = > > > So you're barking up the wrong tree here. The problem I think > > > is that you're just computing requested_crtcs wrong. > > = > > So here in this case, requested CRTC =3D 0x1 since it requests modeset = on CRTC 0 > > Now in teh atomic check, it steals the slave CRTC 1 and hence affected = CRTC comes out > > as 0x3 and hence the mismatch. > = > Hmm. How can it be 0x3 if we filtered out the uapi.enable=3D=3Dfalse case? > = Yes if I add that condition like in this patch then it correctly calculates the affected crtc bitmask as only 0x1 since it doesnt include the slave crt= c. So with this patch, requested crtc =3D 0x 1, affected crtc =3D 0x1 If this looks good then this fixes our bigjoiner warnings. Does this patch look good to you as is then? Manasi > > Now what is not clear to me is that if a full modeset was not required > > why did i915 still steal that slave CRTC? > > = > > Manasi > > = > > > = > > > > If we add this check there then the affected crtc wont count the sl= ave crtc > > > > and we wont get this warning. > > > > = > > > > Ville, Danvet? > > > > = > > > > Manasi > > > > = > > > > = > > > > On Tue, Mar 16, 2021 at 10:35:09PM +0100, Daniel Vetter wrote: > > > > > On Tue, Mar 9, 2021 at 10:14 AM Pekka Paalanen wrote: > > > > > > > > > > > > On Mon, 8 Mar 2021 16:52:58 -0800 > > > > > > "Navare, Manasi" wrote: > > > > > > > > > > > > > On Thu, Mar 04, 2021 at 10:42:23AM +0200, Pekka Paalanen wrot= e: > > > > > > > > On Wed, 3 Mar 2021 12:44:33 -0800 > > > > > > > > "Navare, Manasi" wrote: > > > > > > > > > > > > > > > > > On Wed, Mar 03, 2021 at 10:47:44AM +0200, Pekka Paalanen = wrote: > > > > > > > > > > On Tue, 2 Mar 2021 12:41:32 -0800 > > > > > > > > > > Manasi Navare wrote: > > > > > > > > > > > > > > > > > > > > > In case of a modeset where a mode gets split across m= utiple CRTCs > > > > > > > > > > > in the driver specific implementation (bigjoiner in i= 915) we wrongly count > > > > > > > > > > > the affected CRTCs based on the drm_crtc_mask and ind= icate the stolen CRTC as > > > > > > > > > > > an affected CRTC in atomic_check_only(). > > > > > > > > > > > This triggers a warning since affected CRTCs doent ma= tch requested CRTC. > > > > > > > > > > > > > > > > > > > > > > To fix this in such bigjoiner configurations, we shou= ld only > > > > > > > > > > > increment affected crtcs if that CRTC is enabled in U= API not > > > > > > > > > > > if it is just used internally in the driver to split = the mode. > > > > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > > > I think that makes sense to me. Stealing CRTCs that are= not currently > > > > > > > > > > used by the userspace (display server) should be ok, as= long as that > > > > > > > > > > is completely invisible to userspace: meaning that it d= oes not cause > > > > > > > > > > userspace to unexpectedly e.g. receive or miss per-crtc= atomic > > > > > > > > > > completion events. > > > > > > > > > > > > > > > > > > Yes since we are only doing atomic_check_only() here, the= stolen > > > > > > > > > > > > > > > > But the real not-test-only commit will follow if this test-= only commit > > > > > > > > succeeds, and keeping the guarantees for the real commit ar= e important. > > > > > > > > > > > > > > Hmm well after the actual real commit, since the second crtc = is stolen > > > > > > > even though it is not being used for the display output, it is > > > > > > > used for joiner so the uapi.enable will be true after the rea= l commit. > > > > > > > > > > > > > > so actually the assertion would fail in this case. > > > > > > > > > > > > > > @Ville @Danvet any suggestions here in that case? > > > > > = > > > > > That is very bad. We can't frob uapi state like that. I think that > > > > > calls for even more checks to make sure kms drivers who try to pl= ay > > > > > clever games don't get it wrong, so we probably need to check uapi > > > > > enable and active state in another mask before/after ->atomic_che= ck > > > > > too. Or something like that. > > > > > = > > > > > > Hi, > > > > > > > > > > > > that is not what I was talking about, but sounds like you found= a > > > > > > different problem. It seems like the problem you are talking ab= out > > > > > > would be guaranteed to be hit if bigjoiner was used. Have you n= ot > > > > > > tested this? > > > > > > > > > > > > However, I was talking about the real commit itself, not what h= appens > > > > > > on commits after it, see below. > > > > > > > > > > > > > > > crtc is completely invisible to the userspace and hence t= hat is > > > > > > > > > indicated by uapi.enable which is not true for this stolen > > > > > > > > > crtc. However if allow modeset flag set, then it will do = a full > > > > > > > > > modeset and indicate the uapi.enable for this stolen crtc= as well > > > > > > > > > since that cannot be used for other modeset requested by = userspace. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Can that also be asserted somehow, or does this already= do that? > > > > > > > > > > > > > > > > > > Not clear what you want the assertion for? Could you elab= orate > > > > > > > > > > > > > > > > As assertion that when the real atomic commit happens and t= hen > > > > > > > > completion events are fired, they match exactly the affecte= d crtcs mask. > > > > > > > > > > > > This is my concern and a question, although like I say below, o= nly > > > > > > tangential to this patch. > > > > > > > > > > > > However, as this patch aims to allow bigjoiner usage, naturally= the > > > > > > question will arise whether the completion events then match wh= at > > > > > > userspace expects or not. Userspace does not expect completion = events > > > > > > referring to the stolen CRTCs. > > > > > = > > > > > Yeah we also must make sure that we don't send out events for the= se > > > > > additional crtc in bigjoiner usage. Sounds like igt testing didn't > > > > > catch this, I think we need a lot more igts here to make sure all > > > > > these surprises don't happen. > > > > > = > > > > > Plus maybe triple-checking that drm_atomic_uapi.c makes sure we c= an't > > > > > send out events for stuff that userspace didn't ask for. > > > > > -Daniel > > > > > = > > > > > > > > > > > > > > I understand this may be off-topic for this particular patc= h, but since > > > > > > > > we are discussing the topic, such checks would be really ni= ce. I'm > > > > > > > > curious if such checks already exist. > > > > > > > > > > > > > > > > > > Thanks, > > > > > > pq > > > > > > > > > > > > > > > > > --- > > > > > > > > > > > drivers/gpu/drm/drm_atomic.c | 6 ++++-- > > > > > > > > > > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > > > > > > > > > > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/g= pu/drm/drm_atomic.c > > > > > > > > > > > index 5b4547e0f775..d7acd6bbd97e 100644 > > > > > > > > > > > --- a/drivers/gpu/drm/drm_atomic.c > > > > > > > > > > > +++ b/drivers/gpu/drm/drm_atomic.c > > > > > > > > > > > @@ -1358,8 +1358,10 @@ int drm_atomic_check_only(stru= ct drm_atomic_state *state) > > > > > > > > > > > } > > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > > > - for_each_new_crtc_in_state(state, crtc, new_crt= c_state, i) > > > > > > > > > > > - affected_crtc |=3D drm_crtc_mask(crtc); > > > > > > > > > > > + for_each_new_crtc_in_state(state, crtc, new_crt= c_state, i) { > > > > > > > > > > > + if (new_crtc_state->enable) > > > > > > > > > > > + affected_crtc |=3D drm_crtc_mas= k(crtc); > > > > > > > > > > > + } > > > > > > > > > > > > > > > > > > > > > > /* > > > > > > > > > > > * For commits that allow modesets drivers can = add other CRTCs to the > > > > > > _______________________________________________ > > > > > > dri-devel mailing list > > > > > > dri-devel@lists.freedesktop.org > > > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > > = > > > > > = > > > > > = > > > > > -- = > > > > > Daniel Vetter > > > > > Software Engineer, Intel Corporation > > > > > http://blog.ffwll.ch > > > > _______________________________________________ > > > > dri-devel mailing list > > > > dri-devel@lists.freedesktop.org > > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel > > > = > > > -- = > > > Ville Syrj=E4l=E4 > > > Intel > = > -- = > Ville Syrj=E4l=E4 > Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx