On Wed, Oct 09, 2024 at 03:14:05PM +0200, Stefan Eichenberger wrote: > From: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx> > > The suspend/resume support is broken on the i.MX6QDL platform. This > patch resets the link upon resuming to recover functionality. It shares > most of the sequences with other i.MX devices but does not touch the > critical registers, which might break PCIe. This patch addresses the > same issue as the following downstream commit: > https://github.com/nxp-imx/linux-imx/commit/4e92355e1f79d225ea842511fcfd42b343b32995 > In comparison this patch will also reset the device if possible. Without > this patch suspend/resume will not work if a PCIe device is connected. > The kernel will hang on resume and print an error: > ath10k_pci 0000:01:00.0: Unable to change power state from D3hot to D0, device inaccessible > 8<--- cut here --- > Unhandled fault: imprecise external abort (0x1406) at 0x0106f944 > > Signed-off-by: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx> > --- Thank you for your patch. But it may conflict with another suspend/resume patch https://lore.kernel.org/imx/1727245477-15961-8-git-send-email-hongxing.zhu@xxxxxxx/ Frank > v1 -> v2: Share most code with other i.MX platforms and set suspend > support flag for i.MX6QDL. Version 1 can be found here: > https://lore.kernel.org/all/20240819090428.17349-1-eichest@xxxxxxxxx/ > > drivers/pci/controller/dwc/pci-imx6.c | 44 +++++++++++++++++++++++++-- > 1 file changed, 41 insertions(+), 3 deletions(-) > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c > index 808d1f1054173..f33bef0aa1071 100644 > --- a/drivers/pci/controller/dwc/pci-imx6.c > +++ b/drivers/pci/controller/dwc/pci-imx6.c > @@ -1238,8 +1238,23 @@ static int imx_pcie_suspend_noirq(struct device *dev) > > 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); > + /* > + * Do not turn off the PCIe controller because of ERR003756, ERR004490, ERR005188, > + * they all document issues with LLTSSM and the PCIe controller which > + * does not come out of reset properly. Therefore, try to keep the controller enabled > + * and only reset the link. However, the reference clock still needs to be turned off, > + * else the controller will freeze on resume. > + */ > + if (imx_pcie->drvdata->variant == IMX6Q) { Add new flag: IMX_PCIE_FLAG_SKIP_TURN_OFF. use imx_check_flag() here. Maybe other platform don't want to turn PCIe at some usercase. > + /* Reset the PCIe device */ > + gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 1); > + > + if (imx_pcie->drvdata->enable_ref_clk) > + imx_pcie->drvdata->enable_ref_clk(imx_pcie, false); > + } else { > + imx_pcie_stop_link(imx_pcie->pci); > + imx_pcie_host_exit(pp); > + } > > return 0; > } > @@ -1253,6 +1268,28 @@ static int imx_pcie_resume_noirq(struct device *dev) > if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND)) > return 0; > > + /* > + * Even though the i.MX6Q does not support proper suspend/resume, we > + * need to reset the link after resume or the memory mapped PCIe I/O > + * space will be inaccessible. This will cause the system to freeze. > + */ > + if (imx_pcie->drvdata->variant == IMX6Q) { > + if (imx_pcie->drvdata->enable_ref_clk) > + imx_pcie->drvdata->enable_ref_clk(imx_pcie, true); > + > + imx_pcie_deassert_core_reset(imx_pcie); > + > + /* > + * Setup the root complex again and enable msi. Without this PCIe will > + * not work in msi mode and drivers will crash if they try to access > + * the device memory area > + */ > + dw_pcie_setup_rc(&imx_pcie->pci->pp); > + imx_pcie_msi_save_restore(imx_pcie, false); > + > + return 0; > + } > + > ret = imx_pcie_host_init(pp); > if (ret) > return ret; > @@ -1485,7 +1522,8 @@ 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_SUPPORTS_SUSPEND, Add IMX_PCIE_FLAG_SKIP_TURN_OFF here and move comment "Do not turn off the PCIe" to here. Frank > .dbi_length = 0x200, > .gpr = "fsl,imx6q-iomuxc-gpr", > .clk_names = imx6q_clks, > -- > 2.43.0 >
