Huawei's usage of the subclass and protocol fields is not 100%
clear to us, but there appears to be a very strict system.
A device with the "shared" device ID 12d1:1506 and this NCM
function was recently reported (showing only default altsetting):
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 3
bInterfaceProtocol 22
iInterface 8 CDC Network Control Model (NCM)
** UNRECOGNIZED: 05 24 00 10 01
** UNRECOGNIZED: 06 24 1a 00 01 1f
** UNRECOGNIZED: 0c 24 1b 00 01 00 04 10 14 dc 05 20
** UNRECOGNIZED: 0d 24 0f 0a 0f 00 00 00 ea 05 03 00 01
** UNRECOGNIZED: 05 24 06 01 01
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x85 EP 5 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0010 1x 16 bytes
bInterval 9
Cc: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Messages from the modem exceeding 256 bytes cause communication
failure.
The WDM protocol is strictly "read on demand", meaning that we only
poll for unread data after receiving a notification from the modem.
Since we have no way to know how much data the modem has to send,
we must make sure that the buffer we provide is "big enough".
Message truncation does not work. Truncated messages are left unread
until the modem has another message to send. Which often won't
happen until the userspace application has given up waiting for the
final part of the last message, and therefore sends another command.
With a proper CDC WDM function there is a descriptor telling us
which buffer size the modem uses. But with this vendor specific
implementation there is no known way to calculate the exact "big
enough" number. It is an unknown property of the modem firmware.
Experience has shown that 256 is too small. The discussion of
this failure ended up concluding that 512 might be too small as
well. So 1024 seems like a reasonable value for now.
Fixes: 41c47d8cfd ("net: huawei_cdc_ncm: Introduce the huawei_cdc_ncm driver")
Cc: Enrico Mioso <mrkiko.rs@gmail.com>
Reported-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-By: Enrico Mioso <mrkiko.rs@gmail.com>
Tested-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Calling netif_carrier_{on,off} is sufficient. There is no need
to duplicate the carrier state in a driver specific flag.
Acked-by: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
This driver supports devices using the NCM protocol as an encapsulation layer
for other protocols, like the E3131 Huawei 3G modem. This drivers approach was
heavily inspired by the qmi_wwan/cdc_mbim approach & code model.
Signed-off-by: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
