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PCI: qcom: Wait PCIE_RESET_CONFIG_WAIT_MS after link-up IRQ

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Per PCIe r6.0, sec 6.6.1, software must generally wait a minimum of
100ms (PCIE_RESET_CONFIG_WAIT_MS) after Link training completes before
sending a Configuration Request.

Prior to 36971d6c5a ("PCI: qcom: Don't wait for link if we can detect
Link Up"), qcom used dw_pcie_wait_for_link(), which waited between 0
and 90ms after the link came up before we enumerate the bus, and this
was apparently enough for most devices.

After 36971d6c5a, qcom_pcie_global_irq_thread() started enumeration
immediately when handling the link-up IRQ, and devices (e.g., Laszlo
Fiat's PLEXTOR PX-256M8PeGN NVMe SSD) may not be ready to handle config
requests yet.

Delay PCIE_RESET_CONFIG_WAIT_MS after the link-up IRQ before starting
enumeration.

Fixes: 82a823833f ("PCI: qcom: Add Qualcomm PCIe controller driver")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Link: https://patch.msgid.link/20250625102347.1205584-13-cassel@kernel.org
This commit is contained in:
Niklas Cassel 2025-06-25 12:23:50 +02:00 committed by Manivannan Sadhasivam
parent c7eb9c5e14
commit 15b6b243cc
1 changed files with 1 additions and 0 deletions
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drivers/pci/controller/dwc/pcie-qcom.c
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@ -1564,6 +1564,7 @@ static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data)
writel_relaxed(status, pcie->parf + PARF_INT_ALL_CLEAR);
if (FIELD_GET(PARF_INT_ALL_LINK_UP, status)) {
msleep(PCIE_RESET_CONFIG_WAIT_MS);
dev_dbg(dev, "Received Link up event. Starting enumeration!\n");
/* Rescan the bus to enumerate endpoint devices */
pci_lock_rescan_remove();