Re: Low speed BULK endpoints on UHCI

Greg KH wrote:
> On Tue, Sep 11, 2007 at 01:18:58PM +0400, Brad Campbell wrote:
>> The other option is to find some way of making the usb-serial/generic
>> driver able to substitute interrupt for bulk endpoints where required
>> (and I've spent a bit of time investigating that, but my knowledge of
>> the linux usb stack is pretty shaky)
> 
> If you need to do something like this, then just write your own
> usb-serial driver.  It is quite easy to do that, as what you are looking
> for does not fit into the "generic" usb-serial model.
> 
> Heck, if you provide us with the endpoint signature (output of
> /proc/bus/usb/devices) for your device, I'll be glad to knock out a
> first cut for such a driver, it should not be all that hard.
> 
> thanks,
> 
> greg k-h
> 

Sure, on a kernel with Alan's patch to config.c removed, and the check in uhci-q.c removed, it works
perfectly well with usbserial or cdc_acm as this device.

T:  Bus=01 Lev=02 Prnt=22 Port=01 Cnt=01 Dev#= 23 Spd=1.5 MxCh= 0
D:  Ver= 1.01 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=16c0 ProdID=05e1 Rev= 1.00
S:  Manufacturer=Brads-Propeller
S:  Product=CDC-ACM-HACK
C:* #Ifs= 2 Cfg#= 1 Atr=40 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=cdc_acm
E:  Ad=83(I) Atr=03(Int.) MxPS=   8 Ivl=100ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_acm
E:  Ad=01(O) Atr=02(Bulk) MxPS=   8 Ivl=0ms
E:  Ad=81(I) Atr=02(Bulk) MxPS=   8 Ivl=0ms

Standard bulk endpoint (1) for transmit/receive.

This is what we get on the latest kernels

T:  Bus=01 Lev=02 Prnt=02 Port=01 Cnt=01 Dev#=  3 Spd=1.5 MxCh= 0
D:  Ver= 1.01 Cls=02(comm.) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=16c0 ProdID=05e1 Rev= 1.00
S:  Manufacturer=Brads-Propeller
S:  Product=CDC-ACM-HACK
C:* #Ifs= 2 Cfg#= 1 Atr=40 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=02 Prot=01 Driver=cdc_acm
E:  Ad=83(I) Atr=03(Int.) MxPS=   8 Ivl=100ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_acm
E:  Ad=01(O) Atr=03(Int.) MxPS=   8 Ivl=1ms
E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=1ms

[ 2665.920000] usb 1-1: new full speed USB device using uhci_hcd and address 2
[ 2666.150000] usb 1-1: configuration #1 chosen from 1 choice
[ 2666.150000] hub 1-1:1.0: USB hub found
[ 2666.160000] hub 1-1:1.0: 4 ports detected
[ 2670.400000] usb 1-1.2: new low speed USB device using uhci_hcd and address 3
[ 2670.520000] usb 1-1.2: config 1 interface 1 altsetting 0 endpoint 0x1 is Bulk; changing to Interrupt
[ 2670.520000] usb 1-1.2: config 1 interface 1 altsetting 0 endpoint 0x81 is Bulk; changing to Interrupt
[ 2670.540000] usb 1-1.2: configuration #1 chosen from 1 choice
[ 2670.580000] cdc_acm 1-1.2:1.0: ttyACM0: USB ACM device
[ 2670.590000] usbcore: registered new interface driver cdc_acm
[ 2670.590000] drivers/usb/class/cdc-acm.c: v0.25:USB Abstract Control Model driver for USB modems 
and ISDN adapters

It of course no longer functions.

Investigation continues on the best way to tackle this particular device.

Regards,
Brad
-- 
"Human beings, who are almost unique in having the ability
to learn from the experience of others, are also remarkable
for their apparent disinclination to do so." -- Douglas Adams



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