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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7FFC4CA0ED1 for ; Mon, 18 Aug 2025 17:32:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=DnYkaV7Yi7urfSXkwUZ7oNo2CkgDGXu4HobllhNu8/E=; b=zrbbELk35k1Jx2 2rrm2MG1RMirz+nAUGJtEg/p3HrzSPdBk3sN4T7EM11MgR8KErHX1M0U/QOTOXDygcFR73QtMf19v U4l3fRKxPT8yidTZ3ciPSN2EmactovsfGBI1/MGhZB5intllgdt2HvbvH39BxiTjTzF3uxuHObwiC D3I07aRjXpaFQCs1uiYT6Itdvy+QSM5j/U2lNJKUlwIR0xyWywgqCvJ1CBVWB6NEtsjnXcW3BhW71 J4k1DbSFl5YrJWfgjjwgWXsx4MZ1OfVYROjGQY7MRbLMzw9ASCf3OXiRHizl13fE6AwKmAr2XMSS0 tavISgpYZTzg/ewM7RNw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uo3j1-00000008BKZ-1qBa; Mon, 18 Aug 2025 17:32:51 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uo26B-00000007xAL-1L3T for linux-arm-kernel@lists.infradead.org; Mon, 18 Aug 2025 15:48:40 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 52EDA5C5F5A; Mon, 18 Aug 2025 15:48:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA63DC4CEEB; Mon, 18 Aug 2025 15:48:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755532115; bh=SD+YffITOfZAo6Ivx+38x0kP3WuI7A8ZqDwATXhXXAk=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=rIyUtouvTqSQc8bVuEm61JYDwdCLFA+/97Yamt591o3sfsa8/GSMX85ag89CZO1FZ v1D4Ow4jXJvA7pihd+zjhI07g2ZLM2FQPzV731bIuYu+9IN4WnYcKZAgb6ftVnoSkL N9fiyUUXq32WzdvUDkgZ/NEZtlJGux/7XbfS11rWvZTna6AtjN9gYDmZpsKv51MOod Z2YODUPQQ6yqbesk5Pnpi/mLaMI8IZvsSV8qOLXleFdbWlZgCtoMMDvag0sF3b1xot gbiXzPWL93C5e+vRzRCRRD+1JV/a+47ZeCmhit58trvxI4B2Bn8Ek6TgR4INmDDDGU snoJGHTF31DYg== Date: Mon, 18 Aug 2025 10:48:33 -0500 From: Bjorn Helgaas To: Richard Zhu Cc: frank.li@nxp.com, jingoohan1@gmail.com, l.stach@pengutronix.de, lpieralisi@kernel.org, kwilczynski@kernel.org, mani@kernel.org, robh@kernel.org, bhelgaas@google.com, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [RESEND v3 1/5] PCI: dwc: Don't poll L2 if QUIRK_NOL2POLL_IN_PM is existing in suspend Message-ID: <20250818154833.GA528281@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250818073205.1412507-2-hongxing.zhu@nxp.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250818_084839_400297_5052E538 X-CRM114-Status: GOOD ( 22.32 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Aug 18, 2025 at 03:32:01PM +0800, Richard Zhu wrote: > Refer to PCIe r6.0, sec 5.2, fig 5-1 Link Power Management State Flow > Diagram. Both L0 and L2/L3 Ready can be transferred to LDn directly. > > It's harmless to let dw_pcie_suspend_noirq() proceed suspend after the > PME_Turn_Off is sent out, whatever the LTSSM state is in L2 or L3 after > a recommended 10ms max wait refer to PCIe r6.0, sec 5.3.3.2.1 PME > Synchronization. > > The LTSSM states are inaccessible on i.MX6QP and i.MX7D after the > PME_Turn_Off is sent out. > > To support this case, don't poll L2 state and apply a simple delay of > PCIE_PME_TO_L2_TIMEOUT_US(10ms) if the QUIRK_NOL2POLL_IN_PM flag is set > in suspend. > > Signed-off-by: Richard Zhu > Reviewed-by: Frank Li > --- > .../pci/controller/dwc/pcie-designware-host.c | 31 +++++++++++++------ > drivers/pci/controller/dwc/pcie-designware.h | 4 +++ > 2 files changed, 25 insertions(+), 10 deletions(-) > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c > index 952f8594b5012..20a7f827babbf 100644 > --- a/drivers/pci/controller/dwc/pcie-designware-host.c > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c > @@ -1007,7 +1007,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci) > { > u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP); > u32 val; > - int ret; > + int ret = 0; > > /* > * If L1SS is supported, then do not put the link into L2 as some * devices such as NVMe expect low resume latency. */ if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1) return 0; You didn't change it in this patch (the L1SS test was added by 4774faf854f5 ("PCI: dwc: Implement generic suspend/resume functionality")), but this L1SS check is an encapsulation problem. The ASPM configuration shouldn't leak out here in such an ad hoc way. *All* drivers, not just NVMe, would prefer low resume latency. How do we deal with this in other host controller drivers? If any other driver puts links in L2, I suppose they would have the same issue? Maybe DWC is the only one that puts the link in L2? What happens when we add a new driver that puts links in L2? I guess we'll be debugging some NVMe issue again? Bjorn