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Subject[PATCH v2] PCI/DPC: Fix PCI legacy interrupt acknowledgement
Date
Current DPC driver acknowledges the interrupt in deferred work, which works
since MSI are edge triggered.

But when MSI is disabled (e.g. pci=nomsi boot option) port service
driver falls back to PCI legacy INT interrupt.

With current code we do not acknowledge the interrupt back in dpc_irq()
and we get dpc interrupt storm.

This patch acknowledges the interrupt in interrupt handler.

Signed-off-by: Oza Pawandeep <poza@codeaurora.org>

diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c
index 38e40c6..9c05120 100644
--- a/drivers/pci/pcie/pcie-dpc.c
+++ b/drivers/pci/pcie/pcie-dpc.c
@@ -112,7 +112,7 @@ static void dpc_work(struct work_struct *work)
}

pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
- PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
+ PCI_EXP_DPC_STATUS_TRIGGER);

pci_read_config_word(pdev, cap + PCI_EXP_DPC_CTL, &ctl);
pci_write_config_word(pdev, cap + PCI_EXP_DPC_CTL,
@@ -222,6 +222,9 @@ static irqreturn_t dpc_irq(int irq, void *context)
if (dpc->rp_extensions && reason == 3 && ext_reason == 0)
dpc_process_rp_pio_error(dpc);

+ pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
+ PCI_EXP_DPC_STATUS_INTERRUPT);
+
schedule_work(&dpc->work);

return IRQ_HANDLED;
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.,
a Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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