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

Linux regression tracking (Thorsten Leemhuis)
2024-04-22T17:33:24Z

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.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
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#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
>>
>