Re: [PATCH v3] usb: dwc2/gadget: report disconnect event from 'end session' irq

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Hello,

On 2014-10-31 19:15, Paul Zimmerman wrote:
From: Marek Szyprowski [mailto:m.szyprowski@xxxxxxxxxxx]
Sent: Friday, October 31, 2014 1:04 AM
To: linux-usb@xxxxxxxxxxxxxxx; linux-samsung-soc@xxxxxxxxxxxxxxx
Cc: Marek Szyprowski; Kyungmin Park; Robert Baldyga; Paul Zimmerman; Krzysztof Kozlowski; Felipe Balbi
Subject: [PATCH v3] usb: dwc2/gadget: report disconnect event from 'end session' irq

This patch adds a call to s3c_hsotg_disconnect() from 'end session'
interrupt (GOTGINT_SES_END_DET) to correctly notify gadget subsystem
about unplugged usb cable. 'disconnected' interrupt (DISCONNINT) might
look a bit more suitable for this event, but it is asserted only in
host mode, so in device mode we need to use something else.

Additional check has been added in s3c_hsotg_disconnect() function
to ensure that the event is reported only once after successful device
enumeration.

Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
  drivers/usb/dwc2/core.h   |  1 +
  drivers/usb/dwc2/gadget.c | 10 ++++++++++
  2 files changed, 11 insertions(+)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 55c90c53f2d6..b42df32e7737 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -212,6 +212,7 @@ struct s3c_hsotg {
  	struct usb_gadget       gadget;
  	unsigned int            setup;
  	unsigned long           last_rst;
+	unsigned int		address;
  	struct s3c_hsotg_ep     *eps;
  };

diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
index fcd2bb55ccca..6304efba11aa 100644
--- a/drivers/usb/dwc2/gadget.c
+++ b/drivers/usb/dwc2/gadget.c
@@ -1114,6 +1114,7 @@ static void s3c_hsotg_process_control(struct s3c_hsotg *hsotg,
  				 DCFG_DEVADDR_SHIFT) & DCFG_DEVADDR_MASK;
  			writel(dcfg, hsotg->regs + DCFG);

+			hsotg->address = ctrl->wValue;
  			dev_info(hsotg->dev, "new address %d\n", ctrl->wValue);

  			ret = s3c_hsotg_send_reply(hsotg, ep0, NULL, 0);
@@ -2031,6 +2032,10 @@ static void s3c_hsotg_disconnect(struct s3c_hsotg *hsotg)
  {
  	unsigned ep;

+	if (!hsotg->address)
+		return;
+
+	hsotg->address = 0;
  	for (ep = 0; ep < hsotg->num_of_eps; ep++)
  		kill_all_requests(hsotg, &hsotg->eps[ep], -ESHUTDOWN, true);

@@ -2290,6 +2295,11 @@ irq_retry:
  		dev_info(hsotg->dev, "OTGInt: %08x\n", otgint);

  		writel(otgint, hsotg->regs + GOTGINT);
+
+		if (otgint & GOTGINT_SES_END_DET) {
+			s3c_hsotg_disconnect(hsotg);
+			hsotg->gadget.speed = USB_SPEED_UNKNOWN;
+		}
  	}

  	if (gintsts & GINTSTS_SESSREQINT) {
I don't think this is right. The host can send control requests to
the device before it sends a SetAddress to change from the default
address of 0. So if a GOTGINT_SES_END_DET happens before the
SetAddress, it will be ignored.

Or am I missing something?

Well, right. However before finishing enumeration (setting the address) host usually only retrieves some usb descriptors what doesn't change the state of the gadget. Right now we always reported 'disconnected' event before setting the new address, what is a bit overkill (in some cases gadget driver got this even more than once). The above code handles all cases correctly and reports disconnect event only once.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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