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AJvYcCU2zmOflq6prTh41XQa28OfWVk/UIpUUnaCJiOn7fYtQNOTPw2BEAw7png2POu5lmx7JU0WR+QtjeSs4eI=@vger.kernel.org X-Gm-Message-State: AOJu0Yz5+fIRMByW+NjJR+iq60htJRE1fIf51ZhG44RHNcXz3ihL72VH KKUOivpjvHFv8hz0rDESsZgN8hfL3drJzCu0QVdPK0/6o0XmZ092LKIBfAtgyg== X-Google-Smtp-Source: AGHT+IF/DA7LNyMgu1pnTQkftl5jvkj6Flffim544TjwWV+oZb0jj3oRtdO+6se3chWJxM92S10XOw== X-Received: by 2002:a17:902:ccd2:b0:20c:9026:93a with SMTP id d9443c01a7336-2111946831emr213769535ad.19.1730733130510; Mon, 04 Nov 2024 07:12:10 -0800 (PST) Received: from thinkpad ([2409:40f4:3049:1cc7:217b:63a:40ce:2e01]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21105707e12sm62411805ad.82.2024.11.04.07.12.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Nov 2024 07:12:09 -0800 (PST) Date: Mon, 4 Nov 2024 20:42:02 +0530 From: Manivannan Sadhasivam To: Stefan Eichenberger Cc: hongxing.zhu@nxp.com, l.stach@pengutronix.de, lpieralisi@kernel.org, kw@linux.com, 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: <20241104151202.k6v6fxwyb44n7qw6@thinkpad> References: <20241030103250.83640-1-eichest@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241030103250.83640-1-eichest@gmail.com> 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 Reviewed-by: Manivannan Sadhasivam - Mani > --- > 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 > -- மணிவண்ணன் சதாசிவம்