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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 6BE8DC432C3 for ; Thu, 21 Nov 2019 22:50:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 392AF206DA for ; Thu, 21 Nov 2019 22:50:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UnbOIJS4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726690AbfKUWup (ORCPT ); Thu, 21 Nov 2019 17:50:45 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:52547 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726548AbfKUWuo (ORCPT ); Thu, 21 Nov 2019 17:50:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574376642; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rTk6XMOiYbuw5+XVlipRiSh5UzNmwzHGNqkkTsALVdg=; b=UnbOIJS4bGF1pGLa/PeSaSlC3cw6VP+ch/v2kfa0DENHVHcW0Hc9DRQa5TqQgL1hZJYPtF H0rR+1oXIFtBInJbmbzrrECg4f5CO47ha6f743E22x3+McCZO6wrAPY4/12CTyyH0cxiT1 GQvffRFXpZhgO/utyY2mdQsFVXq85i0= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-381-r4huhGJXOHeCkqYFmD1jqA-1; Thu, 21 Nov 2019 17:50:39 -0500 Received: by mail-qk1-f199.google.com with SMTP id q125so3050199qka.1 for ; Thu, 21 Nov 2019 14:50:39 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=L6kwu2ljuFRHJGSHsZ074oAeIVPpmWLJ+DvKmAed55k=; b=bTLyGB3sGvrmkxARHbmZk5hoWbDaRwNv6wcYOJ3SVGi0dDoJc2+3YgxmyAC9kHwDX3 C/gD0S6Wpu89l6AGI80TzcIodLmgzdlzfTOqGFB6FSvwT7uo+ndA+ISFP0BrFDppk9ZB bAbqdcEBDy6T2ljnt4cp901J6nKhO1mjqGakEzyjFm6Kc2IbXYcFCeJ9I+eTcu6OFtt3 vVn56DifLAjCWGCE35g8YXZbGGbneNO3H1/tDHvM/b6DJ7xdL01Nvs57dzakmkT1TQqc dtrBmoKwtSrVgHGJiEz4XArgCzt+CD3yXiOVTGKqSomtIiLEF4mTaHX8S4gaf6As33nm ALVA== X-Gm-Message-State: APjAAAVi5+xhHIf1Az4R+PBmpItICgGyTLlr7zlsJbNJsWAQhRmbo+kr JHuyi51BiOOCOa0ZWe92dWAV9EUxxKI0x//HjjrwikqBVbDcNU+2OsfcpWasGiJsbtNR0J8lA+n DjwYkb8oEntAO7ir4DFUaTk5bQrIHYjEYRvJoezhz X-Received: by 2002:a37:8285:: with SMTP id e127mr2677673qkd.62.1574376638873; Thu, 21 Nov 2019 14:50:38 -0800 (PST) X-Google-Smtp-Source: APXvYqziB5Ucb8ZFpCpITvN4kvLRDkloqv4Emub8IRaRDSPVC7EbFpNg+VGTx80DbnaXEZuqQUj9nX/wiwQNyS7b2t8= X-Received: by 2002:a37:8285:: with SMTP id e127mr2677652qkd.62.1574376638429; Thu, 21 Nov 2019 14:50:38 -0800 (PST) MIME-Version: 1.0 References: <20191120155301.GL11621@lahna.fi.intel.com> <20191121112821.GU11621@lahna.fi.intel.com> <20191121114610.GW11621@lahna.fi.intel.com> <20191121125236.GX11621@lahna.fi.intel.com> <20191121194942.GY11621@lahna.fi.intel.com> In-Reply-To: From: Karol Herbst Date: Thu, 21 Nov 2019 23:50:26 +0100 Message-ID: Subject: Re: [PATCH v4] pci: prevent putting nvidia GPUs into lower device states on certain intel bridges To: "Rafael J. Wysocki" Cc: Mika Westerberg , Bjorn Helgaas , LKML , Lyude Paul , "Rafael J . Wysocki" , Linux PCI , Linux PM , dri-devel , nouveau , Dave Airlie , Mario Limonciello X-MC-Unique: r4huhGJXOHeCkqYFmD1jqA-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 21, 2019 at 11:39 PM Rafael J. Wysocki wrot= e: > > On Thu, Nov 21, 2019 at 8:49 PM Mika Westerberg > wrote: > > > > On Thu, Nov 21, 2019 at 04:43:24PM +0100, Rafael J. Wysocki wrote: > > > On Thu, Nov 21, 2019 at 1:52 PM Mika Westerberg > > > wrote: > > > > > > > > On Thu, Nov 21, 2019 at 01:46:14PM +0200, Mika Westerberg wrote: > > > > > On Thu, Nov 21, 2019 at 12:34:22PM +0100, Rafael J. Wysocki wrote= : > > > > > > On Thu, Nov 21, 2019 at 12:28 PM Mika Westerberg > > > > > > wrote: > > > > > > > > > > > > > > On Wed, Nov 20, 2019 at 11:29:33PM +0100, Rafael J. Wysocki w= rote: > > > > > > > > > last week or so I found systems where the GPU was under t= he "PCI > > > > > > > > > Express Root Port" (name from lspci) and on those systems= all of that > > > > > > > > > seems to work. So I am wondering if it's indeed just the = 0x1901 one, > > > > > > > > > which also explains Mikas case that Thunderbolt stuff wor= ks as devices > > > > > > > > > never get populated under this particular bridge controll= er, but under > > > > > > > > > those "Root Port"s > > > > > > > > > > > > > > > > It always is a PCIe port, but its location within the SoC m= ay matter. > > > > > > > > > > > > > > Exactly. Intel hardware has PCIe ports on CPU side (these are= called > > > > > > > PEG, PCI Express Graphics, ports), and the PCH side. I think = the IP is > > > > > > > still the same. > > > > > > > > > > > > > > > Also some custom AML-based power management is involved and= that may > > > > > > > > be making specific assumptions on the configuration of the = SoC and the > > > > > > > > GPU at the time of its invocation which unfortunately are n= ot known to > > > > > > > > us. > > > > > > > > > > > > > > > > However, it looks like the AML invoked to power down the GP= U from > > > > > > > > acpi_pci_set_power_state() gets confused if it is not in PC= I D0 at > > > > > > > > that point, so it looks like that AML tries to access devic= e memory on > > > > > > > > the GPU (beyond the PCI config space) or similar which is n= ot > > > > > > > > accessible in PCI power states below D0. > > > > > > > > > > > > > > Or the PCI config space of the GPU when the parent root port = is in D3hot > > > > > > > (as it is the case here). Also then the GPU config space is n= ot > > > > > > > accessible. > > > > > > > > > > > > Why would the parent port be in D3hot at that point? Wouldn't = that be > > > > > > a suspend ordering violation? > > > > > > > > > > No. We put the GPU into D3hot first, > > > > > > OK > > > > > > Does this involve any AML, like a _PS3 under the GPU object? > > > > I don't see _PS3 (nor _PS0) for that object. If I read it right the GPU > > itself is not described in ACPI tables at all. > > OK > > > > > > then the root port and then turn > > > > > off the power resource (which is attached to the root port) resul= ting > > > > > the topology entering D3cold. > > > > > > > > I don't see that happening in the AML though. > > > > > > Which AML do you mean, specifically? The _OFF method for the root > > > port's _PR3 power resource or something else? > > > > The root port's _OFF method for the power resource returned by its _PR3= . > > OK, so without the $subject patch we (1) program the downstream > component (GPU) into D3hot, then we (2) program the port holding it > into D3hot and then we (3) let the AML (_OFF for the power resource > listed by _PR3 under the port object) run. > > Something strange happens at this point (and I guess that _OFF doesn't > even reach the point where it removes power from the port which is why > we see a lock-up). > it does though. I will post the data shortly (with the change in power consumption), as I also want to do the ACPI traces now. > We know that skipping (1) makes things work and we kind of suspect > that skipping (3) would make things work either, but what about doing > (1) and (3) without (2)? > > > > > Basically the difference is that when Windows 7 or Linux (the _REV= =3D=3D5 > > > > check) then we directly do link disable whereas in Windows 8+ we in= voke > > > > LKDS() method that puts the link into L2/L3. None of the fields the= y > > > > access seem to touch the GPU itself. > > > > > > So that may be where the problem is. > > > > > > Putting the downstream component into PCI D[1-3] is expected to put > > > the link into L1, so I'm not sure how that plays with the later > > > attempt to put it into L2/L3 Ready. > > > > That should be fine. What I've seen the link goes into L1 when > > downstream component is put to D-state (not D0) and then it is put back > > to L0 when L2/3 ready is propagated. Eventually it goes into L2 or L3. > > Well, that's the expected behavior, but the observed behavior isn't as > expected. :-) > > > > Also, L2/L3 Ready is expected to be transient, so finally power shoul= d > > > be removed somehow. > > > > There is GPIO for both power and PERST, I think the line here: > > > > \_SB.SGOV (0x01010004, Zero) > > > > is the one that removes power. > > OK > > > > > LKDS() for the first PEG port looks like this: > > > > > > > > P0L2 =3D One > > > > Sleep (0x10) > > > > Local0 =3D Zero > > > > While (P0L2) > > > > { > > > > If ((Local0 > 0x04)) > > > > { > > > > Break > > > > } > > > > > > > > Sleep (0x10) > > > > Local0++ > > > > } > > > > > > > > One thing that comes to mind is that the loop can end even if P0L2 = is > > > > not cleared as it does only 5 iterations with 16 ms sleep between. = Maybe > > > > Sleep() is implemented differently in Windows? I mean Linux may be > > > > "faster" here and return prematurely and if we leave the port into = D0 > > > > this does not happen, or something. I'm just throwing out ideas :) > > > > > > But this actually works for the downstream component in D0, doesn't i= t? > > > > It does and that leaves the link in L0 so it could be that then the > > above AML works better or something. > > That would be my guess. > > > That reminds me, ASPM may have something to do with this as well. > > Not really if D-states are involved. > > > > Also, if the downstream component is in D0, the port actually should > > > stay in D0 too, so what would happen with the $subject patch applied? > > > > Parent port cannot be lower D-state than the child so I agree it should > > stay in D0 as well. However, it seems that what happens is that the > > issue goes away :) > > Well, at least this is kind of out of the spec. > > Note that pci_pm_suspend_noirq() won't let the port go into D3 if the > downstream device is in D0, so the $subject patch will not work as > expected in the suspend-to-idle case. > > Also we really should make up our minds on whether or not to force > PCIe ports to stay in D0 when downstream devices are in D0 and be > consequent about that. Right now we do one thing during system-wide > suspend and the other one in PM-runtime, which is confusing. > > The current design is mostly based on the PCI PM Spec 1.2, so it would > be consequent to follow system-wide suspend in PM-runtime and avoid > putting PCIe ports holding devices in D0 into any low-power states. > but that would make the approach in the $subject patch ineffective. > > Moreover, the fact that there are separate branches for "Windows 7" > and "Windows 8+" kind of suggest a change in the expected behavior > between Windows 7 and Windows 8, from the AML perspective. I would > guess that Windows 7 followed PCI PM 1.2 and Windows 8 (and later) > does something else. Now, the structure of the "Windows 8+" branch > described by you suggests that, at least in the cases when it is going > to remove power from the port eventually, it goes straight for the > link preparation (the L2/L3 Ready transition) and power removal > without bothering to program the downstream device and port into D3hot > (because that's kind of redundant). > > That hypothetical "Windows 8+" approach may really work universally, > because it doesn't seem to break any rules (going straight from D0 to > D3cold is not disallowed and doing that for both a port and a > downstream device at the same time is kind of OK either, as long as > the link is ready for that). >