Date:	Mon, 20 Jul 2015 12:51:48 -0500
From:	Felipe Balbi <balbi@...com>
To:	Subbaraya Sundeep Bhatta <subbaraya.sundeep.bhatta@...inx.com>
CC:	"balbi@...com" <balbi@...com>, John Youn <John.Youn@...opsys.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] usb: dwc3: gadget: return error if command sent
 to DEPCMD register fails

Hi,

On Wed, Jul 15, 2015 at 09:49:05AM +0000, Subbaraya Sundeep Bhatta wrote:
> Hi John,
> 
> > -----Original Message-----
> > From: Felipe Balbi [mailto:balbi@...com]
> > Sent: Tuesday, July 14, 2015 12:29 AM
> > To: John Youn
> > Cc: balbi@...com; Subbaraya Sundeep Bhatta; gregkh@...uxfoundation.org;
> > linux-usb@...r.kernel.org; linux-kernel@...r.kernel.org;
> > stable@...r.kernel.org
> > Subject: Re: [PATCH v2 3/3] usb: dwc3: gadget: return error if command
> > sent to DEPCMD register fails
> > 
> > Hi,
> > 
> > On Mon, Jul 13, 2015 at 05:50:49PM +0000, John Youn wrote:
> > > On 7/11/2015 12:29 PM, Felipe Balbi wrote:
> > > > Hi,
> > > >
> > > > On Sat, Jul 11, 2015 at 05:17:32PM +0000, Subbaraya Sundeep Bhatta
> > wrote:
> > > >>>>>> Hi Felipe,
> > > >>>>>>
> > > >>>>>> Just an update on this.
> > > >>>>>>
> > > >>>>>> I'm trying to get this working with our latest IP with dwc3
> > > >>>>>> from your testing/next branch. It fails the usbtest with a
> > > >>>>>> problem unrelated to this patch.
> > > >>>>>> .
> > > >>>>>> It passes on 4.1.1.
> > > >>>>>>
> > > >>>>>> I'll have to look into the failure but I won't get to it until
> > > >>>>>> next week as I'm off the rest of this week.
> > > >>>>>
> > > >>>>> interesting... If you could post failure signature, I can help
> > > >>>>> looking at it, but I guess it's too late to ask :-)
> > > >>>>>
> > > >>>>> thanks for helping though
> > > >>>>>
> > > >>>>
> > > >>>>
> > > >>>> Hi Felipe,
> > > >>>>
> > > >>>> Nevermind about my issue, it ended up being a setup-related
> > problem.
> > > >>>>
> > > >>>> I actually do see the same error as you due to this series of patches.
> > > >>>> Except I see it happening before even the first iteration. I get
> > > >>>> a completion status of 1 for the Set Endpoint Transfer Resources
> > > >>>> command. I'm not sure why this is.
> > > >>>>
> > > >>>> I don't see any conflict with any previous Transfer Complete.
> > > >>
> > > >> Same behavior at my end too. Fails before first iteration and I get
> > > >> completion status of 1 for Set Endpoint Resource command. Attached
> > > >> the logs of testing done with this patch and without this patch.
> > > >> Without this patch I often see completion status of 1 for Set
> > > >> Endpoint Transfer Resources command for Bulk and Isoc endpoints but
> > > >> test proceeds because driver just logs command completion status
> > > >> and moves on. We can revert this patch for time being. IP version is
> > 2.90a.
> > > >
> > > > yeah, that's what I mean, it really seems like it's the IP misbehaving.
> > > >
> > > > John, let's try to figure out what's the root cause of this, we
> > > > really want to use command completion status at some point, but for
> > > > now we need to revert the patch :-(
> > > >
> > > > Let me know if you want me to log STARS ticket on your solvnet system.
> > > >
> > > > cheers
> > > >
> > >
> > > Hi Felipe,
> > >
> > > We found the issue last week.
> > >
> > > The start config command isn't getting called during SET_INTERFACE.
> > > Thus the transfer resource index isn't getting reset, and with
> > > multiple SET_INTERFACE commands it will eventually exhaust the
> > > resources.
> > >
> > > I tried out a fix and it works for me. I'll send it out separately for
> > > review.
> 
> Thanks John for debugging :). Yes we are not handling SET_INTERFACE similar to
> SET_CONFIGURATION in driver. I guess we follow 
> "Alternate Initialization on SetInterface Request" sequence as per data book.
> Felipe can confirm this.
> 
> > 
> > Thanks a lot John. Not sure how come we missed that for such a long time
> > :-) Let's Cc stable and get it plugged ASAP :-)
> > 
> > > Also, I noticed that the trace message that shows control transfers
> > > doesn't show the SET_INTERFACE properly. Any idea why this is?
> > >
> > > For example, here is the line in the trace that corresponds to the
> > > SET_INTERFACE:
> > > irq/33-dwc3-10808 [003] d...  2443.494368: dwc3_ctrl_req:
> > bRequestType
> > > 01 bRequest 0b wValue 0001 wIndex 0000 wLength 0
> 
> Can you please elaborate? What is expected here? Did you mean it shows wrong info
> (other than the request actually sent by Host) ?

I have been looking more at this and the reason why we're failing is a
patch from Paul, which I quote below:

commit b23c843992b659d537514e6493d673284f5d6724
Author: Paul Zimmerman <Paul.Zimmerman@...opsys.com>
Date:   Fri Sep 30 10:58:42 2011 +0300

    usb: dwc3: gadget: fix DEPSTARTCFG for non-EP0 EPs
    
    DEPSTARTCFG for non-EP0 EPs must only be sent once per config
    
    [ balbi@...com : changed config_start to start_config_issued ]
    
    Signed-off-by: Paul Zimmerman <paulz@...opsys.com>
    Signed-off-by: Felipe Balbi <balbi@...com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 0231eba1f53d..502582ce1fc6 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -529,6 +529,7 @@ static inline void dwc3_trb_to_nat(struct dwc3_trb_hw *hw, struct dwc3_trb *nat)
  * @ep0_status_pending: ep0 status response without a req is pending
  * @ep0_bounced: true when we used bounce buffer
  * @ep0_expect_in: true when we expect a DATA IN transfer
+ * @start_config_issued: true when StartConfig command has been issued
  * @ep0_next_event: hold the next expected event
  * @ep0state: state of endpoint zero
  * @link_state: link state
@@ -576,6 +577,7 @@ struct dwc3 {
 	unsigned		ep0_status_pending:1;
 	unsigned		ep0_bounced:1;
 	unsigned		ep0_expect_in:1;
+	unsigned		start_config_issued:1;
 
 	enum dwc3_ep0_next	ep0_next_event;
 	enum dwc3_ep0_state	ep0state;
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index cc27c4ec498d..2def48ed30ea 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -455,6 +455,7 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 	u32 cfg;
 	int ret;
 
+	dwc->start_config_issued = false;
 	cfg = le16_to_cpu(ctrl->wValue);
 
 	switch (dwc->dev_state) {
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index b2820aa9fa46..9c0174a8f46c 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -237,8 +237,12 @@ static int dwc3_gadget_start_config(struct dwc3 *dwc, struct dwc3_ep *dep)
 	if (dep->number != 1) {
 		cmd = DWC3_DEPCMD_DEPSTARTCFG;
 		/* XferRscIdx == 0 for ep0 and 2 for the remaining */
-		if (dep->number > 1)
+		if (dep->number > 1) {
+			if (dwc->start_config_issued)
+				return 0;
+			dwc->start_config_issued = true;
 			cmd |= DWC3_DEPCMD_PARAM(2);
+		}
 
 		return dwc3_send_gadget_ep_cmd(dwc, 0, cmd, &params);
 	}
@@ -1161,6 +1165,8 @@ static int dwc3_gadget_start(struct usb_gadget *g,
 	reg |= DWC3_DCFG_SUPERSPEED;
 	dwc3_writel(dwc->regs, DWC3_DCFG, reg);
 
+	dwc->start_config_issued = false;
+
 	/* Start with SuperSpeed Default */
 	dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
 
@@ -1592,6 +1598,7 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
 
 	dwc3_stop_active_transfers(dwc);
 	dwc3_disconnect_gadget(dwc);
+	dwc->start_config_issued = false;
 
 	dwc->gadget.speed = USB_SPEED_UNKNOWN;
 }
@@ -1643,6 +1650,7 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
 
 	dwc3_stop_active_transfers(dwc);
 	dwc3_clear_stall_all_ep(dwc);
+	dwc->start_config_issued = false;
 
 	/* Reset device address to zero */
 	reg = dwc3_readl(dwc->regs, DWC3_DCFG);


So the problem is that even though endpoint *is* indeed disabled,
start_config_issued is still true and we return before sending that
command. According to Paul's patch it's important that we send
start_config only once per config.

However, I do see that section 9.1.5, table 9-5 of Databook 2.90a has no
conditionals around DEPSTARTCFG. Reverting that patch from Paul, I can
see that it all works fine.

I'll send the revert still today, but I need you guys to confirm that it
really works on your platforms. According to Paul he "can't see how the
driver would work without" start_config_issued trick.

cheers

-- 
balbi

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