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 72109C4450A for ; Thu, 16 Jul 2026 22:27:13 +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=1xljQTmqJlCzKIHpALxY+4GD7OjjFlayegI2A0zHBXY=; b=tyJvpwm/3SWVQW 39GIL4AlXFlz+CVReGJwKl9Fp3F5CPP/G2/YS2ANeBDEzlRNLL1nFz2zlBT0ZhDIMfHo0Fp182viF 5w9jJAVMJ/MukZmHg/WKSrABAiwePa9CNoSTpGbiTdVp9PK/tmElg4ty1zgi+NWGjgsmbK5puyJt6 HSBf6J9ujm20QI6TMJWVqk2tCKrnKSi1TGKjUIHS0ue/zviNuWxuJ456qTdbCn6zkNYDvd5qJxbIJ yhzLDUZCu2L17g+EkmyxvdX+mj9LXwGwEvtdJSfpqscMzKbfdHO7iL0VNtrlVQ027jA+RHHJaTDOu zFQhH4juTyDykKg8KThQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wkUXr-00000000jOI-0LnE; Thu, 16 Jul 2026 22:27:07 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wkUXq-00000000jO4-1ns5 for linux-arm-kernel@lists.infradead.org; Thu, 16 Jul 2026 22:27:06 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id D4E5140322; Thu, 16 Jul 2026 22:27:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88F1B1F000E9; Thu, 16 Jul 2026 22:27:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784240825; bh=1xljQTmqJlCzKIHpALxY+4GD7OjjFlayegI2A0zHBXY=; h=Date:From:To:Cc:Subject:In-Reply-To; b=UPpLHQ452t47t7yKSVf2NY5R05kKElpfJvJu4gfkdUp4VGi/FyRTWbsAkzD0HKGEk eOU5MY0FbwoQ5El9idrCMexlCd44Kxls9YZDsBScrje6Fs8MVyPyiV8ngXCHCmkjQa FjD/UsPU7oIi4130Lfpc+hxylmLL0M8RRRDXnCu9TnJlKz8MmWFXLQPuOlyF3WFU29 jOk6xjqNZU5Zuk+zpiQ2NJTXgvmL55f3lRt7dDmc3WOCzU/UpWpQUnp/bB7/EGLQCV z6flHmUHuXrqzuqmt9V9TO8R/j2A2vPSjWDl1e954cHcQ7nVj6xQ7USFR6y98zTfSl NQJhQfXCnmGcw== Date: Thu, 16 Jul 2026 17:27:04 -0500 From: Bjorn Helgaas To: Soeren Moch Cc: Bjorn Helgaas , stable@vger.kernel.org, Richard Zhu , Frank Li , Manivannan Sadhasivam , Lucas Stach , Fabio Estevam , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] PCI: imx6: Keep Root Port MSI capability also for i.MX6Q Message-ID: <20260716222704.GA240248@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260716214054.47372-1-smoch@web.de> 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 Thu, Jul 16, 2026 at 11:40:54PM +0200, Soeren Moch wrote: > On the NXP i.MX6Q chipset MSIs from the endpoints won't be received by > the iMSI-RX MSI controller if the Root Port MSI capability is disabled. > > Even though the Root Port MSIs won't be received by the iMSI-RX controller > due to design, this chipset has some weird hardware bug that prevents > the endpoint MSIs from reaching when the Root Port MSI capability is > disabled. > > Hence, always keep the Root Port MSI capability for this chipset. > > Note that by keeping Root Port MSI capability, Root Port MSIs such as AER, > PME and others won't be received by default. So users need to use > workarounds such as passing 'pcie_pme=nomsi' cmdline param. I'd like to align the subject a little more with 3a4e8302e72f and avoid repeating the ".. from reaching when the Root Port MSI ..." part of the commit log, which seems to be missing a word. So I propose the following (if you think it's accurate): PCI: imx6: Keep i.MX6Q Root Port MSI capability with iMSI-RX to work around hardware bug On some NXP chipsets, disabling Root Port MSI/MSI-X Capabilities blocks MSIs originating from Endpoints from reaching the iMSI-RX controller. To address this hardware bug, 3a4e8302e72f ("PCI: imx6: Keep Root Port MSI capability with iMSI-RX to work around hardware bug") preserves Root Port MSI and MSI-X Capabilities on i.MX7D, i.MX8MM, and i.MX8MQ when iMSI-RX is in use. The same applies to i.MX6Q, so preserve Root Port MSI/MSI-X Capabilities there as well. Note that preserving these Capabilities means Root Port-originated MSIs such as AER and PME won't be received due to separate hardware limitations. Users may need to use workarounds such as passing the 'pcie_pme=nomsi' command-line parameter. Also, we need to resolve the Sashiko question about whether IMX6QP and IMX6SX also need this. NXP folks, can you verify? > Fixes: f5cd8a929c825 ("PCI: dwc: Remove MSI/MSIX capability for Root Port if iMSI-RX is used as MSI controller") > Cc: # 7.0+ > Signed-off-by: Soeren Moch > Acked-by: Richard Zhu > Reviewed-by: Frank Li > Reviewed-by: Manivannan Sadhasivam > --- > Cc: Manivannan Sadhasivam > Cc: Richard Zhu > Cc: Lucas Stach > Cc: Bjorn Helgaas > Cc: Frank Li > Cc: Fabio Estevam > Cc: linux-pci@vger.kernel.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: imx@lists.linux.dev > Cc: linux-kernel@vger.kernel.org > > This patch is similar to > 3a4e8302e72f ("PCI: imx6: Keep Root Port MSI capability with iMSI-RX to work around hardware bug") > > Tested on a tbs2910 board [1] > [1] arch/arm/boot/dts/nxp/imx/imx6q-tbs2910.dts > > changes in v2: > - collect a-b and r-b tags > - use correct fixes tag (Manivannan) > (reference commit that introduced the bug, not the incomplete fix) > > Since this is a fix for a regression in linux-7.0+, can this still be merged for 7.2-rcS ? > --- > drivers/pci/controller/dwc/pci-imx6.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > index 98e1db751132..8130cf93c2bb 100644 > --- a/drivers/pci/controller/dwc/pci-imx6.c > +++ b/drivers/pci/controller/dwc/pci-imx6.c > @@ -1995,7 +1995,8 @@ static const struct imx_pcie_drvdata drvdata[] = { > .flags = IMX_PCIE_FLAG_IMX_PHY | > IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND | > IMX_PCIE_FLAG_BROKEN_SUSPEND | > - IMX_PCIE_FLAG_SUPPORTS_SUSPEND, > + IMX_PCIE_FLAG_SUPPORTS_SUSPEND | > + IMX_PCIE_FLAG_KEEP_MSI_CAP, > .dbi_length = 0x200, > .gpr = "fsl,imx6q-iomuxc-gpr", > .ltssm_off = IOMUXC_GPR12, > -- > 2.43.0 >