WARN: Success on ctrl setup TRB without IOC set??

On Fri, Feb 09, 2018 at 09:59:46AM +0800, Peter Chen wrote:

On Wed, Feb 07, 2018 at 03:43:23PM +0200, Mathias Nyman wrote:

quoted

On 07.02.2018 11:45, Peter Chen wrote:

quoted

Hi Mathias,

I am implementing USB2 EHSET SINGLE_STEP_SET_FEATURE Test for XHCI port,
(see ehset_single_step_set_feature for EHCI), it needs to set IOC
for setup packet, and software waits 15 seconds before DATA + STATUS stage.
After porting such design for XHCI, it triggers above warning, and
returns -ESHUTDOWN for URB. Any reasons why we don't allow completion
interrupt for SETUP stage? Thanks.

Current xhci driver control transfer implementation doesn't support
queuing a control transfer in parts. we set the IOC only for the status
stage, and we always queue a status stage (and possibly data stage) automatically
when queuing a control transfer URB.

If we get a success event for the SETUP stage the driver will finish the TD and
return the whole URB.

For testing  purposes you would need to make sure we don't call finish_td() for
a success event at the SETUP stage, something like this (untested):

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index c5cbc68..f6d005e 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c

@@ -2014,12 +2014,8 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
        switch (trb_comp_code) {
        case COMP_SUCCESS:
-               if (trb_type != TRB_STATUS) {
-                       xhci_warn(xhci, "WARN: Success on ctrl %s TRB without IOC set?\n",
-                                 (trb_type == TRB_DATA) ? "data" : "setup");
-                       *status = -ESHUTDOWN;
-                       break;
-               }
+               if (trb_type == TRB_SETUP)
+                       return 0;
                *status = 0;
                break;
        case COMP_SHORT_PACKET:

Thanks, Mathias. I need to call finish_td since it needs to
giveback and cleanup URB. And I see below code at process_ctrl_td,
why we can't call it? In fact, I only see warning message, but
without any errors for transactions. How about only delete message
or change debug level as xhci_dbg?

Should be "or change debug message level and *status value as zero."

	/* stopped at setup stage, no data transferred */
	if (trb_type == TRB_SETUP)
		goto finish_td;

--