On Mon, Aug 19, 2024 at 11:03:16AM +0200, Stefan Eichenberger wrote: > On the i.MX6Quad (not QuadPlus), the PCIe link does not work after a > suspend/resume cycle. Worse, the PCIe memory mapped I/O isn't accessible > at all, so the system freezes when a PCIe driver tries to access its I/O > space. The only way to get resume working again is to reset the PCIe > link, similar to what is done on devices that support suspend/resume. > Through trial and error, we found that something about the PCIe > reference clock does not work as expected after a resume. We could not > figure out if it is disabled (even though the registers still say it is > enabled), or if it is somehow unstable or has some hiccups. With the > workaround introduced in this patch series, we were able to fully resume > a Compex WLE900VX (ath10k) miniPCIe Wifi module and an Intel AX200 M.2 > Wifi module. If there is a better way or other ideas on how to fix this > problem, please let us know. We are aware that resetting the link should > not be necessary, but we could not find a better solution. More > interestingly, even the SoCs that support suspend/resume according to > the i.MX erratas seem to reset the link on resume in > imx6_pcie_host_init, so we hope this might be a valid workaround. > > Stefan Eichenberger (3): > PCI: imx6: Add a function to deassert the reset gpio > PCI: imx6: move the wait for clock stabilization to enable ref clk > PCI: imx6: reset link on resume Thanks you for your patch, but it may have conflict with https://lore.kernel.org/linux-pci/Zr4XG6r+HnbIlu8S@lizhi-Precision-Tower-5810/T/#t > > drivers/pci/controller/dwc/pci-imx6.c | 69 +++++++++++++++++++++++---- > 1 file changed, 59 insertions(+), 10 deletions(-) > > -- > 2.43.0 >
