Message ID | 20240817-pci-qcom-ep-cleanup-v1-1-d6b958226559@linaro.org |
---|---|
State | Handled Elsewhere |
Headers | show |
Series | PCI: {qcom-ep/tegra194}: Move endpoint cleanups to PERST# deassert handler | expand |
Hello, > Currently, the endpoint cleanup function dw_pcie_ep_cleanup() and EPF > deinit notify function pci_epc_deinit_notify() are called during the > execution of qcom_pcie_perst_assert() i.e., when the host has asserted > PERST#. But quickly after this step, refclk will also be disabled by the > host. > > All of the Qcom endpoint SoCs supported as of now depend on the refclk from > the host for keeping the controller operational. Due to this limitation, > any access to the hardware registers in the absence of refclk will result > in a whole endpoint crash. Unfortunately, most of the controller cleanups > require accessing the hardware registers (like eDMA cleanup performed in > dw_pcie_ep_cleanup(), powering down MHI EPF etc...). So these cleanup > functions are currently causing the crash in the endpoint SoC once host > asserts PERST#. > > One way to address this issue is by generating the refclk in the endpoint > itself and not depending on the host. But that is not always possible as > some of the endpoint designs do require the endpoint to consume refclk from > the host (as I was told by the Qcom engineers). > > So let's fix this crash by moving the controller cleanups to the start of > the qcom_pcie_perst_deassert() function. qcom_pcie_perst_deassert() is > called whenever the host has deasserted PERST# and it is guaranteed that > the refclk would be active at this point. So at the start of this function > (after enabling resources), the controller cleanup can be performed. Once > finished, rest of the code execution for PERST# deassert can continue as > usual. Applied to controller/qcom, thank you! [01/01] PCI: qcom-ep: Move controller cleanups to qcom_pcie_perst_deassert() https://git.kernel.org/pci/pci/c/7d7cf89b119a Krzysztof
diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c index 236229f66c80..5d31285685b6 100644 --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c @@ -389,6 +389,10 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci) return ret; } + /* Perform cleanup that requires refclk */ + pci_epc_deinit_notify(pci->ep.epc); + dw_pcie_ep_cleanup(&pci->ep); + /* Assert WAKE# to RC to indicate device is ready */ gpiod_set_value_cansleep(pcie_ep->wake, 1); usleep_range(WAKE_DELAY_US, WAKE_DELAY_US + 500); @@ -522,8 +526,6 @@ static void qcom_pcie_perst_assert(struct dw_pcie *pci) { struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci); - pci_epc_deinit_notify(pci->ep.epc); - dw_pcie_ep_cleanup(&pci->ep); qcom_pcie_disable_resources(pcie_ep); pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED; }