Re: Trouble with usb modem

On 10/10/07, jidong xiao <[email protected]> wrote:
>
> Judging from the log file of 2.6.5, there usb_new_device fails when it
> call usb_get_device_descriptor.
>
> In 2.6.22, hub_port_init() and usb_new_device() are invoked twice,the
> first try fails and the second try got succeed.
>
> Since from 2.6.10 we introduce a new USB device initialization scheme,
> I feel maybe your device is incompatible with the old scheme and only
> works against the new scheme.
>
> Regards
> Jason
>

And we can take a look at the source code of 2.6.5,

   1117         for (i = 0; i < NEW_DEVICE_RETRYS; ++i) {
   1118
   1119                 for (j = 0; j < SET_ADDRESS_RETRYS; ++j) {
   1120                         err = usb_set_address(dev);
   1121                         if (err >= 0)
   1122                                 break;
   1123                         wait_ms(200);
   1124                 }
   1125                 if (err < 0) {
   1126                         dev_err(&dev->dev,
   1127                                 "device not accepting address
%d, error %d\n",
   1128                                 dev->devnum, err);
   1129                         goto fail;
   1130                 }
   1131
   1132                 wait_ms(10);    /* Let the SET_ADDRESS settle */
   1133
   1134                 /* high and low speed devices don't need this... */
   1135                 err = usb_get_device_descriptor(dev, 8);
   1136                 if (err >= 8)
   1137                         break;
   1138                 wait_ms(100);
   1139         }
   1140
   1141         if (err < 8) {
   1142                 dev_err(&dev->dev, "device descriptor read/8,
error %d\n", err);
   1143                 goto fail;
   1144         }

NEW_DEVICE_RETRYS is defined as a value of 2. So
usb_get_device_descriptor will be called twice, but after the loop,
err is still less than 8, which induces line 1142 being executed.(we
could see this error message in your log file.)

So I highly suspect your device is not compatible with the old scheme.

Regards
Jason

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