| Message ID | 20250505092603.286623-8-cassel@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | PCI: dwc: Link Up IRQ fixes | expand |
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c index 6b18a2775e7f..5cef5e92b173 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -1646,6 +1646,7 @@ static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data) if (FIELD_GET(PARF_INT_ALL_LINK_UP, status)) { dev_dbg(dev, "Received Link up event. Starting enumeration!\n"); + msleep(PCIE_T_RRS_READY_MS); /* Rescan the bus to enumerate endpoint devices */ pci_lock_rescan_remove(); pci_rescan_bus(pp->bridge->bus);
Commit 36971d6c5a9a ("PCI: qcom: Don't wait for link if we can detect Link Up") changed so that we no longer call dw_pcie_wait_for_link(), and instead enumerate the bus when receiving a Link Up IRQ. Before 36971d6c5a9a, we called dw_pcie_wait_for_link(), and in the first iteration of the loop, the link will never be up (because the link was just started), dw_pcie_wait_for_link() will then sleep for LINK_WAIT_SLEEP_MS (90 ms), before trying again. This means that even if a driver was missing a msleep(PCIE_T_RRS_READY_MS) (100 ms), because of the call to dw_pcie_wait_for_link(), enumerating the bus would essentially be delayed by that time anyway (because of the sleep LINK_WAIT_SLEEP_MS (90 ms)). While we could add the msleep(PCIE_T_RRS_READY_MS) after deasserting PERST (qcom already has an unconditional 1 ms sleep after deasserting PERST), that would essentially bring back an unconditional delay during probe (the whole reason to use a Link Up IRQ was to avoid an unconditional delay during probe). Thus, add the msleep(PCIE_T_RRS_READY_MS) before enumerating the bus in the IRQ handler. This way, for qcom SoCs that has a link up IRQ, we will not have a 100 ms unconditional delay during boot for unpopulated PCIe slots. Fixes: 36971d6c5a9a ("PCI: qcom: Don't wait for link if we can detect Link Up") Signed-off-by: Niklas Cassel <cassel@kernel.org> --- drivers/pci/controller/dwc/pcie-qcom.c | 1 + 1 file changed, 1 insertion(+)