hwtracing: hisi_ptt: Handle the interrupt in hardirq context

Handle the trace interrupt in the hardirq context, make sure the irq
core won't threaded it by declaring IRQF_NO_THREAD and userspace won't
balance it by declaring IRQF_NOBALANCING. Otherwise we may violate the
synchronization requirements of the perf core, referenced to the
change of arm-ccn PMU
  commit 0811ef7 ("bus: arm-ccn: fix PMU interrupt flags").

In the interrupt handler we mainly doing 2 things:
- Copy the data from the local DMA buffer to the AUX buffer
- Commit the data in the AUX buffer

Signed-off-by: Yicong Yang <[email protected]>
Acked-by: Jonathan Cameron <[email protected]>
[ Fixed commit description to suppress checkpatch warning ]
Signed-off-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Yicong Yang

drivers/hwtracing/ptt/hisi_ptt.c

@@ -342,9 +342,9 @@ static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
 		return ret;
 
 	hisi_ptt->trace_irq = pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ);
-	ret = devm_request_threaded_irq(&pdev->dev, hisi_ptt->trace_irq,
-					NULL, hisi_ptt_isr, 0,
-					DRV_NAME, hisi_ptt);
+	ret = devm_request_irq(&pdev->dev, hisi_ptt->trace_irq, hisi_ptt_isr,
+				IRQF_NOBALANCING | IRQF_NO_THREAD, DRV_NAME,
+				hisi_ptt);
 	if (ret) {
 		pci_err(pdev, "failed to request irq %d, ret = %d\n",
 			hisi_ptt->trace_irq, ret);