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

Takashi Iwai
2024-04-22T19:24:17Z

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
> > >>
> > >
> >