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 2906EC433DB for ; Fri, 19 Mar 2021 20:48:05 +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 D219C6197B for ; Fri, 19 Mar 2021 20:48:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D219C6197B 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 766E06EAB4; Fri, 19 Mar 2021 20:48:04 +0000 (UTC) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by gabe.freedesktop.org (Postfix) with ESMTPS id A87FE6EAB4; Fri, 19 Mar 2021 20:48:03 +0000 (UTC) IronPort-SDR: Q7BeQBhJC77EQ8GYAODd6fAft6pLVsbw8AF7fz7D+gvmEm7i//4kST85JAG0RG+nT1/4gEyfBR +T9bx4h9V1tg== X-IronPort-AV: E=McAfee;i="6000,8403,9928"; a="187618231" X-IronPort-AV: E=Sophos;i="5.81,262,1610438400"; d="scan'208";a="187618231" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2021 13:48:03 -0700 IronPort-SDR: GGbfnzjDAKmj11H3Tm18ZN+R3k3W40weQDqzt41BnD85l97ZA4H1CkVAN4mzUgPUcAHK0XG17Q L0tZON5G8bng== X-IronPort-AV: E=Sophos;i="5.81,262,1610438400"; d="scan'208";a="373184028" Received: from labuser-z97x-ud5h.jf.intel.com (HELO labuser-Z97X-UD5H) ([10.165.21.211]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2021 13:48:02 -0700 Date: Fri, 19 Mar 2021 13:54:13 -0700 From: "Navare, Manasi" To: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Message-ID: <20210319205413.GA6359@labuser-Z97X-UD5H> References: <20210302204132.12058-1-manasi.d.navare@intel.com> <20210303104744.2c064f09@eldfell> <20210303204433.GA15819@labuser-Z97X-UD5H> <20210304104223.6b3490bc@eldfell> <20210309005252.GA27491@labuser-Z97X-UD5H> <20210309111350.3be0543f@eldfell> <20210318230126.GA1900@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 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_modeset f= lag. > = > 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 shou= ld 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 C= RTC 0 Now in teh atomic check, it steals the slave CRTC 1 and hence affected CRTC= comes out as 0x3 and hence the mismatch. 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 slave = 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 wrote: > > > > > > On Wed, 3 Mar 2021 12:44:33 -0800 > > > > > > "Navare, Manasi" wrote: > > > > > > > > > > > > > On Wed, Mar 03, 2021 at 10:47:44AM +0200, Pekka Paalanen wrot= e: > > > > > > > > On Tue, 2 Mar 2021 12:41:32 -0800 > > > > > > > > Manasi Navare wrote: > > > > > > > > > > > > > > > > > In case of a modeset where a mode gets split across mutip= le CRTCs > > > > > > > > > in the driver specific implementation (bigjoiner in i915)= we wrongly count > > > > > > > > > the affected CRTCs based on the drm_crtc_mask and indicat= e the stolen CRTC as > > > > > > > > > an affected CRTC in atomic_check_only(). > > > > > > > > > This triggers a warning since affected CRTCs doent match = requested CRTC. > > > > > > > > > > > > > > > > > > To fix this in such bigjoiner configurations, we should o= nly > > > > > > > > > increment affected crtcs if that CRTC is enabled in UAPI = 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 lon= g as that > > > > > > > > is completely invisible to userspace: meaning that it does = not cause > > > > > > > > userspace to unexpectedly e.g. receive or miss per-crtc ato= mic > > > > > > > > completion events. > > > > > > > > > > > > > > Yes since we are only doing atomic_check_only() here, the sto= len > > > > > > > > > > > > But the real not-test-only commit will follow if this test-only= commit > > > > > > succeeds, and keeping the guarantees for the real commit are im= portant. > > > > > > > > > > Hmm well after the actual real commit, since the second crtc is s= tolen > > > > > 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 real co= mmit. > > > > > > > > > > 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 play > > > clever games don't get it wrong, so we probably need to check uapi > > > enable and active state in another mask before/after ->atomic_check > > > 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 about > > > > would be guaranteed to be hit if bigjoiner was used. Have you not > > > > tested this? > > > > > > > > However, I was talking about the real commit itself, not what happe= ns > > > > on commits after it, see below. > > > > > > > > > > > crtc is completely invisible to the userspace and hence that = is > > > > > > > indicated by uapi.enable which is not true for this stolen > > > > > > > crtc. However if allow modeset flag set, then it will do a fu= ll > > > > > > > modeset and indicate the uapi.enable for this stolen crtc as = well > > > > > > > since that cannot be used for other modeset requested by user= space. > > > > > > > > > > > > > > > > > > > > > > > Can that also be asserted somehow, or does this already do = that? > > > > > > > > > > > > > > Not clear what you want the assertion for? Could you elaborate > > > > > > > > > > > > As assertion that when the real atomic commit happens and then > > > > > > completion events are fired, they match exactly the affected cr= tcs mask. > > > > > > > > This is my concern and a question, although like I say below, only > > > > tangential to this patch. > > > > > > > > However, as this patch aims to allow bigjoiner usage, naturally the > > > > question will arise whether the completion events then match what > > > > userspace expects or not. Userspace does not expect completion even= ts > > > > referring to the stolen CRTCs. > > > = > > > Yeah we also must make sure that we don't send out events for these > > > 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 can't > > > send out events for stuff that userspace didn't ask for. > > > -Daniel > > > = > > > > > > > > > > I understand this may be off-topic for this particular patch, b= ut since > > > > > > we are discussing the topic, such checks would be really nice. = 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/gpu/d= rm/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(struct d= rm_atomic_state *state) > > > > > > > > > } > > > > > > > > > } > > > > > > > > > > > > > > > > > > - for_each_new_crtc_in_state(state, crtc, new_crtc_st= ate, i) > > > > > > > > > - affected_crtc |=3D drm_crtc_mask(crtc); > > > > > > > > > + for_each_new_crtc_in_state(state, crtc, new_crtc_st= ate, i) { > > > > > > > > > + if (new_crtc_state->enable) > > > > > > > > > + affected_crtc |=3D drm_crtc_mask(cr= tc); > > > > > > > > > + } > > > > > > > > > > > > > > > > > > /* > > > > > > > > > * 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 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx