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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 8C926C46470 for ; Wed, 8 Aug 2018 06:30:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A56621719 for ; Wed, 8 Aug 2018 06:30:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A56621719 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sntech.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727185AbeHHIsj (ORCPT ); Wed, 8 Aug 2018 04:48:39 -0400 Received: from gloria.sntech.de ([185.11.138.130]:56742 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726894AbeHHIsj (ORCPT ); Wed, 8 Aug 2018 04:48:39 -0400 Received: from wd0970.dip.tu-dresden.de ([141.76.111.202] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1fnHz8-00035x-L1; Wed, 08 Aug 2018 08:30:18 +0200 From: Heiko Stuebner To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Joerg Roedel , Jeffy Chen Subject: Re: [PATCH 1/2] iommu/rockchip: Handle errors returned from PM framework Date: Wed, 08 Aug 2018 08:30:17 +0200 Message-ID: <8919220.oqSeQNaOOv@phil> In-Reply-To: <5aa8d184-0c58-3471-a661-8a66a93271c7@arm.com> References: <20180807085406.3863-1-marc.zyngier@arm.com> <3265383.PcPThIO4HC@phil> <5aa8d184-0c58-3471-a661-8a66a93271c7@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am Dienstag, 7. August 2018, 16:25:53 CEST schrieb Marc Zyngier: > On 07/08/18 14:15, Heiko Stuebner wrote: > > Am Dienstag, 7. August 2018, 14:31:49 CEST schrieb Marc Zyngier: > >> On 07/08/18 13:09, Heiko Stuebner wrote: > >>> Hi Marc, > >>> > >>> Am Dienstag, 7. August 2018, 10:54:05 CEST schrieb Marc Zyngier: > >>>> pm_runtime_get_if_in_use can fail: either PM has been disabled > >>>> altogether (-EINVAL), or the device hasn't been enabled yet (0). > >>>> Sadly, the Rockchip IOMMU driver tends to conflate the two things > >>>> by considering a non-zero return value as successful. > >>>> > >>>> This has the consequence of hiding other bugs, so let's handle this > >>>> case throughout the driver, with a WARN_ON_ONCE so that we can try > >>>> and work out what happened. > >>>> > >>>> Fixes: 0f181d3cf7d98 ("iommu/rockchip: Add runtime PM support") > >>>> Signed-off-by: Marc Zyngier > >>> > >>> I'm still not sure about the !CONFIG_PM case, as it was probably silently > >>> working in that case before > >> > >> Do we agree that this is an orthogonal problem though? > > > > Nope ;-) .... I.e. right now the code ignores the -EINVAL from disabled PM > > and continues, possibly even handling the irq correctly. > > Ah, I now see what you mean. Yeah, this is a bit rubbish. It would have > been better if the API returned something more sensible in that case, > but that's a bit late... > > > If it actually worked is a different matter, as I guess nobody really tried > > with !PM in the past. > > I don't think anyone noticed. !CONFIG_PM on something like rk3399 > probably isn't very popular, and certainly comes for free on a > multiplatform kernel. > > > Now with error-handling we always return IRQ_NONE for !PM. > > Yup. > > >>> But on the other hand we're also already running over it in other places > >>> like in the iommu-shutdown and I guess if someone _really_ disabled > >>> CONFIG_PM, a lot of additional stuff would fail anyway. > >>> > >>> So should we wrap that in some #ifdef magic, just ignore it or simply > >>> select PM similar to what Tegra, Renesas and Vexpress seem to do? > >>> > >>> I guess I like the 3rd option best ;-) > >> > >> It probably doesn't hurt. At what level do you want it? As a dependency > >> to the IOMMU? or to the platform? > > > > I guess it might be best to go the Tegra, etc way. Whoever in their right > > mind would want to drive a mobile platform without any form for power > > management ;-) . > > > > I can do these patches for arm32+arm64 myself ... I just wanted to put > > that thought out there - in case that was just a stupid idea of mine :-D . > > Not stupid at all. Regarding this very patch: where do you want me to > take it? If you want to add select PM for Rockchip yourself (32+64 bit), just send them regularly and maybe include arm@kernel.org directly, so they can apply them directly, with just a reviewed-by tag from me. Heiko