Re: Regression due to 59cf44575456 ("USB: core: Fix oversight in SuperSpeed initialization")

[Takashi Iwai <tiwai@suse.de>]

On Mon, 22 Apr 2024 20:03:46 +0200,
Alan Stern wrote:
> 
> On Mon, Apr 22, 2024 at 07:33:21PM +0200, Linux regression tracking (Thorsten Leemhuis) wrote:
> > Hi, Thorsten here, the Linux kernel's regression tracker. Top-posting
> > for once, to make this easily accessible to everyone.
> > 
> > Is anyone still working on fixing below regression? From here it looks
> > stalled, but I might have missed something.
> 
> I've been waiting to hear back from Oliver or Takashi.  A revised patch 
> taking my comments into account would be welcome; it should be a very 
> small change (just one or two lines of code).

As posted in another mail, it's a virtualized environment.
Details are found in the original bug report
  https://bugzilla.suse.com/show_bug.cgi?id=1220569

About the patch change: I appreciate if you cook it rather by
yourself since I'm not 100% sure what you suggested.  I can
provide the reporter a test kernel with the patch for confirmation, of
course.


thanks,

Takashi

> 
> Alan Stern
> 
> > Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> > --
> > Everything you wanna know about Linux kernel regression tracking:
> > https://linux-regtracking.leemhuis.info/about/#tldr
> > If I did something stupid, please tell me, as explained on that page.
> > 
> > #regzbot poke
> > 
> > On 09.04.24 16:56, Alan Stern wrote:
> > > On Tue, Apr 09, 2024 at 03:49:01PM +0200, Oliver Neukum wrote:
> > >> Hi,
> > >>
> > >> with the following device:
> > >>
> > >> Bus 002 Device 002: ID fb5d:0001 BHYVE HID Tablet
> > >> Device Descriptor:
> > >>   bLength                18
> > >>   bDescriptorType         1
> > >>   bcdUSB               3.00
> > >>   bDeviceClass            0
> > >>   bDeviceSubClass         0
> > >>   bDeviceProtocol         0
> > >>   bMaxPacketSize0         8
> > > 
> > > A USB-3 device, running at SuperSpeed with its bMaxPacketSize0 set to 8 
> > > instead of 9?  Presumably this thing never received a USB certification.  
> > > Does the packaging use the USB logo?
> > > 
> > >>   idVendor           0xfb5d
> > >>   idProduct          0x0001
> > >>   bcdDevice            0.00
> > >>   iManufacturer           1 BHYVE
> > >>   iProduct                2 HID Tablet
> > >>   iSerial                 3 01
> > >>   bNumConfigurations      1
> > > 
> > > Why on earth would an HID tablet need to run at SuperSpeed?
> > > 
> > >> Binary Object Store Descriptor:
> > >>   bLength                 5
> > >>   bDescriptorType        15
> > >>   wTotalLength       0x000f
> > >>   bNumDeviceCaps          1
> > >>   SuperSpeed USB Device Capability:
> > >>     bLength                10
> > >>     bDescriptorType        16
> > >>     bDevCapabilityType      3
> > >>     bmAttributes         0x00
> > >>     wSpeedsSupported   0x0008
> > >>       Device can operate at SuperSpeed (5Gbps)
> > >>     bFunctionalitySupport   3
> > >>       Lowest fully-functional device speed is SuperSpeed (5Gbps)
> > >>     bU1DevExitLat          10 micro seconds
> > >>     bU2DevExitLat          32 micro seconds
> > > 
> > > A tablet not capable of running at any speed below 5 Gbps?
> > > 
> > >> we are getting a regression on enumeration. It used to work with the
> > >> code prior to your patch. Takashi is proposing the attached fixed.
> > >> It looks like we are a bit too restrictive and should just try.
> > >>
> > >> 	Regards
> > >> 		Oliver
> > > 
> > >> From: Takashi Iwai <tiwai@suse.de>
> > >> Subject: [PATCH] USB: hub: Workaround for buggy max packet size with super
> > >>  speed
> > >> Patch-mainline: Not yet, testing
> > >> References: bsc#1220569
> > >>
> > >> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> > >>
> > >> ---
> > >>  drivers/usb/core/hub.c | 13 ++++++++++---
> > >>  1 file changed, 10 insertions(+), 3 deletions(-)
> > >>
> > >> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> > >> index e38a4124f610..64193effc456 100644
> > >> --- a/drivers/usb/core/hub.c
> > >> +++ b/drivers/usb/core/hub.c
> > >> @@ -4830,7 +4830,7 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> > >>  	const char		*driver_name;
> > >>  	bool			do_new_scheme;
> > >>  	const bool		initial = !dev_descr;
> > >> -	int			maxp0;
> > >> +	int			maxp0, ep0_maxp;
> > >>  	struct usb_device_descriptor	*buf, *descr;
> > >>  
> > >>  	buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
> > >> @@ -5070,7 +5070,8 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> > >>  		else
> > >>  			i = 0;		/* Invalid */
> > >>  	}
> > >> -	if (usb_endpoint_maxp(&udev->ep0.desc) == i) {
> > >> +	ep0_maxp = usb_endpoint_maxp(&udev->ep0.desc);
> > >> +	if (ep0_maxp == i) {
> > > 
> > > This variable looks like it was left over from earlier testing.  It's 
> > > not really needed.
> > > 
> > >>  		;	/* Initial ep0 maxpacket guess is right */
> > >>  	} else if ((udev->speed == USB_SPEED_FULL ||
> > >>  				udev->speed == USB_SPEED_HIGH) &&
> > >> @@ -5082,9 +5083,15 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
> > >>  			dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i);
> > >>  		udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
> > >>  		usb_ep0_reinit(udev);
> > >> +	} else if (udev->speed >= USB_SPEED_SUPER && initial) {
> > >> +		/* FIXME: should be more restrictive? */
> > >> +		/* Initial guess is wrong; use the descriptor's value */
> > >> +		dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i);
> > >> +		udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
> > >> +		usb_ep0_reinit(udev);
> > > 
> > > This could be merged with the previous case fairly easily.
> > > 
> > >>  	} else {
> > >>  		/* Initial guess is wrong and descriptor's value is invalid */
> > >> -		dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", maxp0);
> > >> +		dev_err(&udev->dev, "Invalid ep0 maxpacket: %d, expected %d\n", maxp0, ep0_maxp);
> > > 
> > > This also looks like a remnant from earlier testing.
> > > 
> > > Alan Stern
> > > 
> > >>  		retval = -EMSGSIZE;
> > >>  		goto fail;
> > >>  	}
> > >> -- 
> > >> 2.35.3
> > >>
> > > 
> >