quoted

quoted

+            tmode = le16_to_cpu(ctrl->wIndex);
+
+            if (!set || (tmode & 0xff) != 0)
+                    return -EINVAL;
+
+            switch (tmode >> 8) {
+            case TEST_J:
+            case TEST_K:
+            case TEST_SE0_NAK:
+            case TEST_PACKET:
+                    cdns3_set_register_bit(&priv_dev->regs->usb_cmd,
+                                           USB_CMD_STMODE |
+                                           USB_STS_TMODE_SEL(tmode - 1));

I'm 90% sure this won't work. There's a reason why we only enter the
requested test mode from status stage. How have you tested this?

What's the reason?
It can work although the code is a little different with above, I
tested it using USBxHSETT tool at Windows.

From USB spec:
"The transition to test mode must be complete no later than 3 ms after the completion of the status stage of the
request."
But I don't remember any issues with this test on other ours drivers. Maybe status stage
is armed in this case by controller. I have to confirm how it works with hardware team.
Driver doesn't know when status stage was completed. We don't have
any event on status stage completion.  I haven't checked it yet with tester on this driver.

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+    irqreturn_t ret = IRQ_NONE;
+    unsigned long flags;
+    u32 reg;
+
+    priv_dev = cdns->gadget_dev;
+    spin_lock_irqsave(&priv_dev->lock, flags);

you're already running in hardirq context. Why do you need this lock at
all? I would be better to use the hardirq handler to mask your
interrupts, so they don't fire again, then used the top-half (softirq)
handler to actually handle the interrupts.

This controller may be ran at SMP environment, register and flag access
needs to be protected among CPUs running.

Yes, spin_lock_irqsave is not necessary here.

Do you mean replacing devm_request_irq with a request_threaded_irq ?
I have single interrupt line shared between  Host, Driver, DRD/OTG.
I'm not sure if it will work more efficiently.

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+    /* check USB device interrupt */
+    reg = readl(&priv_dev->regs->usb_ists);
+    writel(reg, &priv_dev->regs->usb_ists);
+
+    if (reg) {
+            dev_dbg(priv_dev->dev, "IRQ: usb_ists: %08X\n", reg);

I strongly advise against using dev_dbg() for debugging. Even more so
inside your IRQ handler.

Felipe, I use Dynamic Debug for debugging, and show debug messages with
"dmesg" after testing/debugging. I see dwc3 using trace,  any benefits
for switching
to trace?

Ok, It's not necessary in this place, especially, that there is invoked trace point
inside cdns3_check_usb_interrupt_proceed which makes the same.

Peter