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 5AD6BE6F07F for ; Fri, 1 Nov 2024 19:37:26 +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=TfjN2FkupChScPj51tVFnwRpzYeduDtz6rkLr7e6vqw=; b=XG+FNVugRq9qwG 02ajl2JxrgVJZ/SQDsy8yj41PtMg3iQp6Udp2czDLW2I5MC89EgA95UlOUxPGxpTHS3BC/Mm9PQtJ zOCGQsKxDsnFUTShL437BBJSlO30PgnYniaJ4kpJpP8KxVMIiaat7XwXEaMpB+wFCTBuReW9bqNgd BTy7CCzgzOBvU2lcAWID0Q0pNQbwFL+L3w3VDlr4xEtQqVUeqVisxP/iBdzyW3R049QPL0aSkhcR6 qjs4T+LJnNRsBeK/Zgb0C7Ze6p1FviBbo+F0G5i5Lo4TXc+mrPXCksJITv+Wb8kJjp3Z+SN+3Cbik LKa/6yQoPHoJkUtt5GVw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t6xSL-000000089aX-0LLE; Fri, 01 Nov 2024 19:37:13 +0000 Received: from nyc.source.kernel.org ([147.75.193.91]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t6xPT-000000088tA-2fFC for linux-arm-kernel@lists.infradead.org; Fri, 01 Nov 2024 19:34:17 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 0C678A44960; Fri, 1 Nov 2024 19:32:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13110C4CECD; Fri, 1 Nov 2024 19:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730489654; bh=7e9jDreQwHjgDrpNnSCJNcACMMOlV2ucUiJHzRNtnGQ=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=Gy+q2VQMdeHnjT5y9u5t9/F6PhF4uzgoSRel0mDRxxSyq3QjYHlyR4JkyEpXP8DV3 NeeZZkqknM2VXeMV9BBFpQDx5/GPmVVoWetU6spQS9H2CQ3fzgckmHv3TmKRx9CNOF 9LamE0J7mmr/CfZm2sXjfEBuujzSZdz7fwU9dP8P/IceaUMELWqXxj6a5Jp2kNdgo1 lTV8bFkOtCBbVdt4w5kdTXRqpo2esomrCNQqXTliqOkebr1XfYjhQxMGHIF41TFvlE cFF9mSY87h88i+ZHBUH+zvZzdw5IQllMK89EDpz4QgXnua1Kz00jrJw6m4A26J6BJi Ar+DeHd6YbhrA== Date: Fri, 1 Nov 2024 14:34:12 -0500 From: Bjorn Helgaas To: Stefan Eichenberger , Richard Zhu , Lucas Stach Cc: lpieralisi@kernel.org, kw@linux.com, manivannan.sadhasivam@linaro.org, robh@kernel.org, bhelgaas@google.com, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, francesco.dolcini@toradex.com, Frank.li@nxp.com, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, linux-kernel@vger.kernel.org, Stefan Eichenberger Subject: Re: [PATCH v4] PCI: imx6: Add suspend/resume support for i.MX6QDL Message-ID: <20241101193412.GA1317741@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241030103250.83640-1-eichest@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241101_123415_839735_BD8CEF7A X-CRM114-Status: GOOD ( 35.82 ) 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 Wed, Oct 30, 2024 at 11:32:45AM +0100, Stefan Eichenberger wrote: > From: Stefan Eichenberger > > The suspend/resume functionality is currently broken on the i.MX6QDL > platform, as documented in the NXP errata (ERR005723): > https://www.nxp.com/docs/en/errata/IMX6DQCE.pdf > > This patch addresses the issue by sharing most of the suspend/resume > sequences used by other i.MX devices, while avoiding modifications to > critical registers that disrupt the PCIe functionality. It targets the > same problem as the following downstream commit: > https://github.com/nxp-imx/linux-imx/commit/4e92355e1f79d225ea842511fcfd42b343b32995 > > Unlike the downstream commit, this patch also resets the connected PCIe > device if possible. Without this reset, certain drivers, such as ath10k > or iwlwifi, will crash on resume. The device reset is also done by the > driver on other i.MX platforms, making this patch consistent with > existing practices. > > Without this patch, suspend/resume will fail on i.MX6QDL devices if a > PCIe device is connected. Upon resuming, the kernel will hang and > display an error. Here's an example of the error encountered with the > ath10k driver: > ath10k_pci 0000:01:00.0: Unable to change power state from D3hot to D0, device inaccessible > Unhandled fault: imprecise external abort (0x1406) at 0x0106f944 > > Signed-off-by: Stefan Eichenberger Richard and Lucas, does this look OK to you? Since you're listed as maintainers of pci-imx6.c, I'd like to have your ack before merging this. > --- > Changes in v4: > - Improve commit message (Bjorn) > - Fix style issue on comments (Bjorn) > - s/msi/MSI (Bjorn) > > Changes in v3: > - Added a new flag to the driver data to indicate that the suspend/resume > is broken on the i.MX6QDL platform. (Frank) > - Fix comments to be more relevant (Mani) > - Use imx_pcie_assert_core_reset in suspend (Mani) > > drivers/pci/controller/dwc/pci-imx6.c | 57 +++++++++++++++++++++------ > 1 file changed, 46 insertions(+), 11 deletions(-) > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > index 808d1f1054173..c8d5c90aa4d45 100644 > --- a/drivers/pci/controller/dwc/pci-imx6.c > +++ b/drivers/pci/controller/dwc/pci-imx6.c > @@ -82,6 +82,11 @@ enum imx_pcie_variants { > #define IMX_PCIE_FLAG_HAS_SERDES BIT(6) > #define IMX_PCIE_FLAG_SUPPORT_64BIT BIT(7) > #define IMX_PCIE_FLAG_CPU_ADDR_FIXUP BIT(8) > +/* > + * Because of ERR005723 (PCIe does not support L2 power down) we need to > + * workaround suspend resume on some devices which are affected by this errata. > + */ > +#define IMX_PCIE_FLAG_BROKEN_SUSPEND BIT(9) > > #define imx_check_flag(pci, val) (pci->drvdata->flags & val) > > @@ -1237,9 +1242,19 @@ static int imx_pcie_suspend_noirq(struct device *dev) > return 0; > > imx_pcie_msi_save_restore(imx_pcie, true); > - imx_pcie_pm_turnoff(imx_pcie); > - imx_pcie_stop_link(imx_pcie->pci); > - imx_pcie_host_exit(pp); > + if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_BROKEN_SUSPEND)) { > + /* > + * The minimum for a workaround would be to set PERST# and to > + * set the PCIE_TEST_PD flag. However, we can also disable the > + * clock which saves some power. > + */ > + imx_pcie_assert_core_reset(imx_pcie); > + imx_pcie->drvdata->enable_ref_clk(imx_pcie, false); > + } else { > + imx_pcie_pm_turnoff(imx_pcie); > + imx_pcie_stop_link(imx_pcie->pci); > + imx_pcie_host_exit(pp); > + } > > return 0; > } > @@ -1253,14 +1268,32 @@ static int imx_pcie_resume_noirq(struct device *dev) > if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND)) > return 0; > > - ret = imx_pcie_host_init(pp); > - if (ret) > - return ret; > - imx_pcie_msi_save_restore(imx_pcie, false); > - dw_pcie_setup_rc(pp); > + if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_BROKEN_SUSPEND)) { > + ret = imx_pcie->drvdata->enable_ref_clk(imx_pcie, true); > + if (ret) > + return ret; > + ret = imx_pcie_deassert_core_reset(imx_pcie); > + if (ret) > + return ret; > + /* > + * Using PCIE_TEST_PD seems to disable MSI and powers down the > + * root complex. This is why we have to setup the rc again and > + * why we have to restore the MSI register. > + */ > + ret = dw_pcie_setup_rc(&imx_pcie->pci->pp); > + if (ret) > + return ret; > + imx_pcie_msi_save_restore(imx_pcie, false); > + } else { > + ret = imx_pcie_host_init(pp); > + if (ret) > + return ret; > + imx_pcie_msi_save_restore(imx_pcie, false); > + dw_pcie_setup_rc(pp); > > - if (imx_pcie->link_is_up) > - imx_pcie_start_link(imx_pcie->pci); > + if (imx_pcie->link_is_up) > + imx_pcie_start_link(imx_pcie->pci); > + } > > return 0; > } > @@ -1485,7 +1518,9 @@ static const struct imx_pcie_drvdata drvdata[] = { > [IMX6Q] = { > .variant = IMX6Q, > .flags = IMX_PCIE_FLAG_IMX_PHY | > - IMX_PCIE_FLAG_IMX_SPEED_CHANGE, > + IMX_PCIE_FLAG_IMX_SPEED_CHANGE | > + IMX_PCIE_FLAG_BROKEN_SUSPEND | > + IMX_PCIE_FLAG_SUPPORTS_SUSPEND, > .dbi_length = 0x200, > .gpr = "fsl,imx6q-iomuxc-gpr", > .clk_names = imx6q_clks, > -- > 2.43.0 >