linux-kernel - RE: [PATCH v9 7/7] usb: Adding SuperSpeed support to dummy

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Date:	Thu, 12 May 2011 08:19:53 +0300
From:	"Tanya Brokhman" <tlinder@...eaurora.org>
To:	"'Sebastian Andrzej Siewior'" <bigeasy@...utronix.de>
Cc:	<greg@...ah.com>, <linux-usb@...r.kernel.org>,
	<linux-arm-msm@...r.kernel.org>, <balbi@...com>,
	<ablay@...eaurora.org>,
	"'open list'" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v9 7/7] usb: Adding SuperSpeed support to dummy_hcd

> > static int dummy_hcd_probe(struct platform_device *pdev)
> > {
> >-	struct usb_hcd		*hcd;
> >+	struct usb_hcd		*hs_hcd;
> >+	struct usb_hcd		*ss_hcd;
> > 	int			retval;
> >
> > 	dev_info(&pdev->dev, "%s, driver " DRIVER_VERSION "\n",
> driver_desc);
> >
> >-	hcd = usb_create_hcd(&dummy_hcd, &pdev->dev, dev_name(&pdev-
> >dev));
> >-	if (!hcd)
> >+	hs_hcd = usb_create_hcd(&dummy_hcd, &pdev->dev, dev_name(&pdev-
> >dev));
> >+	if (!hs_hcd)
> > 		return -ENOMEM;
> >-	the_controller = hcd_to_dummy (hcd);
> >
> >-	retval = usb_add_hcd(hcd, 0, 0);
> >-	if (retval != 0) {
> >-		usb_put_hcd (hcd);
> >-		the_controller = NULL;
> >+	hs_hcd->speed = HCD_USB2;
> Why do you overwrite the speed here and in ->reset()?

You're right. No need for this. I'll remove the above line and the speed
will be set at dummy_setup (->reset())

> >+
> >+	retval = usb_add_hcd(hs_hcd, 0, IRQF_DISABLED | IRQF_SHARED);
> Why IRQF_DISABLED | IRQF_SHARED? you don't interrupts at all.

I used xhci as reference for this patch. This is the way xhci driver adds
the hcds. You can find it in xhci_pci_probe(). 
I'm not very familiar with how this two hcds (main and shared shcd) will
work together so I thought these flags are needed for their co-operation. 
Was my assumption mistaken? What flags should I use? 

Also, Sergei pointed out that IRQF_DISABLED is deprecated so it seems to me
that xhci needs an update as well....

> >+	if (retval != 0)
> >+		usb_put_hcd(hs_hcd);
> Your error recovery is broken here. You have to leave instead of
> continue with SS.
> 

Thanks for catching that!

Best regards,
Tanya Brokhman
Consultant for Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum

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