-----Original Message----- From: Bjorn Helgaas helgaas@kernel.org Sent: 2025年9月25日 4:00 To: Hongxing Zhu hongxing.zhu@nxp.com Cc: Frank Li frank.li@nxp.com; jingoohan1@gmail.com; l.stach@pengutronix.de; lpieralisi@kernel.org; kwilczynski@kernel.org; mani@kernel.org; robh@kernel.org; bhelgaas@google.com; shawnguo@kernel.org; s.hauer@pengutronix.de; kernel@pengutronix.de; festevam@gmail.com; linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org; imx@lists.linux.dev; linux-kernel@vger.kernel.org; stable@vger.kernel.org Subject: Re: [PATCH v6 3/4] PCI: dwc: Skip PME_Turn_Off message if there is no endpoint connected
On Wed, Sep 24, 2025 at 03:23:23PM +0800, Richard Zhu wrote:
A chip freeze is observed on i.MX7D when PCIe RC kicks off the PM_PME message and no any devices are connected on the port.
s/no any/no/
To workaroud such kind of issue, skip PME_Turn_Off message if there is no endpoint connected.
s/workaroud/work around/
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/pcie-designware-host.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 57a1ba08c427..b303a74b0fd7 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -1008,12 +1008,15 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci) u32 val; int ret;
- if (pci->pp.ops->pme_turn_off) {
pci->pp.ops->pme_turn_off(&pci->pp);- } else {
ret = dw_pcie_pme_turn_off(pci);if (ret)return ret;
- /* Skip PME_Turn_Off message if there is no endpoint connected */
- if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_WAIT) {
This looks racy and it sounds like this is a workaround for an i.MX7D defect. Should it be some kind of quirk just for i.MX7D?
Up to now, it is used to fix the issue encountered by i.MX7D PCIe. If the LTSSM stat is changed, for example one device is new inserted if Hot-Plug is supported. The procedure of PME_Turn_Off kick off would terminated by the hot-plug event I think.
Best Regards Richard Zhu
if (pci->pp.ops->pme_turn_off) {pci->pp.ops->pme_turn_off(&pci->pp);} else {ret = dw_pcie_pme_turn_off(pci);if (ret)return ret;}}
if (dwc_quirk(pci, QUIRK_NOL2POLL_IN_PM)) {
-- 2.37.1