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.

Cc: stable@vger.kernel.org Fixes: 4774faf854f5 ("PCI: dwc: Implement generic suspend/resume functionality") Fixes: a528d1a72597 ("PCI: imx6: Use DWC common suspend resume method") Signed-off-by: Richard Zhu hongxing.zhu@nxp.com Reviewed-by: Frank Li Frank.Li@nxp.com --- drivers/pci/controller/dwc/pci-imx6.c | 4 +++ .../pci/controller/dwc/pcie-designware-host.c | 34 +++++++++++++------ drivers/pci/controller/dwc/pcie-designware.h | 4 +++ 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c index 4668fc9648bff..d84bfcd1079ce 100644 --- a/drivers/pci/controller/dwc/pci-imx6.c +++ b/drivers/pci/controller/dwc/pci-imx6.c @@ -125,6 +125,7 @@ struct imx_pcie_drvdata { enum imx_pcie_variants variant; enum dw_pcie_device_mode mode; u32 flags; + u32 quirk; int dbi_length; const char *gpr; const u32 ltssm_off; @@ -1765,6 +1766,7 @@ static int imx_pcie_probe(struct platform_device *pdev) if (ret) return ret;

+ pci->quirk_flag = imx_pcie->drvdata->quirk; pci->use_parent_dt_ranges = true; if (imx_pcie->drvdata->mode == DW_PCIE_EP_TYPE) { ret = imx_add_pcie_ep(imx_pcie, pdev); @@ -1849,6 +1851,7 @@ static const struct imx_pcie_drvdata drvdata[] = { .enable_ref_clk = imx6q_pcie_enable_ref_clk, .core_reset = imx6qp_pcie_core_reset, .ops = &imx_pcie_host_ops, + .quirk = QUIRK_NOL2POLL_IN_PM, }, [IMX7D] = { .variant = IMX7D, @@ -1860,6 +1863,7 @@ static const struct imx_pcie_drvdata drvdata[] = { .mode_mask[0] = IMX6Q_GPR12_DEVICE_TYPE, .enable_ref_clk = imx7d_pcie_enable_ref_clk, .core_reset = imx7d_pcie_core_reset, + .quirk = QUIRK_NOL2POLL_IN_PM, }, [IMX8MQ] = { .variant = IMX8MQ, diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 20c9333bcb1c4..09b50a5ce19bb 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -1144,15 +1144,29 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci) return ret; }

- ret = read_poll_timeout(dw_pcie_get_ltssm, val, - val == DW_PCIE_LTSSM_L2_IDLE || - val <= DW_PCIE_LTSSM_DETECT_WAIT, - PCIE_PME_TO_L2_TIMEOUT_US/10, - PCIE_PME_TO_L2_TIMEOUT_US, false, pci); - if (ret) { - /* Only log message when LTSSM isn't in DETECT or POLL */ - dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val); - return ret; + if (dwc_quirk(pci, QUIRK_NOL2POLL_IN_PM)) { + /* + * Add the QUIRK_NOL2_POLL_IN_PM case to avoid the read hang, + * when LTSSM is not powered in L2/L3/LDn properly. + * + * 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. On the LTSSM states poll broken + * platforms, add a max 10ms delay refer to PCIe r6.0, + * sec 5.3.3.2.1 PME Synchronization. + */ + mdelay(PCIE_PME_TO_L2_TIMEOUT_US/1000); + } else { + ret = read_poll_timeout(dw_pcie_get_ltssm, val, + val == DW_PCIE_LTSSM_L2_IDLE || + val <= DW_PCIE_LTSSM_DETECT_WAIT, + PCIE_PME_TO_L2_TIMEOUT_US/10, + PCIE_PME_TO_L2_TIMEOUT_US, false, pci); + if (ret) { + /* Only log message when LTSSM isn't in DETECT or POLL */ + dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n", val); + return ret; + } }

/* @@ -1168,7 +1182,7 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)

pci->suspended = true;

- return ret; + return 0; } EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);

diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h index e995f692a1ecd..1fdaed1562b7a 100644 --- a/drivers/pci/controller/dwc/pcie-designware.h +++ b/drivers/pci/controller/dwc/pcie-designware.h @@ -297,6 +297,9 @@ /* Default eDMA LLP memory size */ #define DMA_LLP_MEM_SIZE PAGE_SIZE

+#define QUIRK_NOL2POLL_IN_PM BIT(0) +#define dwc_quirk(pci, val) (pci->quirk_flag & val) + struct dw_pcie; struct dw_pcie_rp; struct dw_pcie_ep; @@ -511,6 +514,7 @@ struct dw_pcie { const struct dw_pcie_ops *ops; u32 version; u32 type; + u32 quirk_flag; unsigned long caps; int num_lanes; int max_link_speed;