On Wed, Aug 19, 2020 at 7:40 AM Maciej Żenczykowski
<zenczykowski@xxxxxxxxx> wrote:
> All the dongles I've looked at seem to place MaxBurst just after MaxPacketSize,
> and not in a separate descriptor (and don't place burst on the
> status/config channel).
You're right, that looks wrong. In my patches, the companion
descriptor sets max burst of 15 on ss_ncm_notify_comp_desc (and
ss_ncm_notify_comp_desc), which is an interrupt IN endpoint with a max
packet size of 16. This probably doesn't make sense, and in any case
is prohibited by the spec:
======
The only allowable maximum data payload size for interrupt endpoints
is 1024 bytes for interrupt endpoints that support a burst size
greater than one and can be any size from 1 to 1024 for an interrupt
endpoint with a burst size equal to one. The maximum allowable burst
size for interrupt endpoints is three.
======
Will respin this series to leave ss_ncm_notify_comp_desc and
ssp_ncm_notify_comp_desc at a burst of 0.
> What does "lsusb -d ... -v" show from the host side?
Output when on a 10 Gbps link:
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 2 Communications
bFunctionSubClass 13
bFunctionProtocol 0
iFunction 7 CDC NCM
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 2 Communications
bInterfaceSubClass 13
bInterfaceProtocol 0
iInterface 4 CDC Network Control Model (NCM)
CDC Header:
bcdCDC 1.10
CDC Union:
bMasterInterface 0
bSlaveInterface 1
CDC Ethernet:
iMacAddress 5 fab33fdead72
bmEthernetStatistics 0x00000000
wMaxSegmentSize 1514
wNumberMCFilters 0x0000
bNumberPowerFilters 0
CDC NCM:
bcdNcmVersion 1.00
bmNetworkCapabilities 0x11
crc mode
packet filter
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0010 1x 16 bytes
bInterval 9
bMaxBurst 15
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This looks wrong, see above.
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 10 CDC Data
bInterfaceSubClass 0
bInterfaceProtocol 1
iInterface 6 CDC Network Data
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 2
bInterfaceClass 10 CDC Data
bInterfaceSubClass 0
bInterfaceProtocol 1
iInterface 6 CDC Network Data
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 0
bMaxBurst 15
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This looks correct (max burst of 15 on the bulk in endpoint).
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0400 1x 1024 bytes
bInterval 0
bMaxBurst 15
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This looks correct (max burst of 15 on the bulk out endpoint).
