[Nut-upsdev] usbhid-ups fails with Belkin F6C120-UNV in nut-2.4.3
Arjen de Korte
nut+devel at de-korte.org
Sun Mar 21 10:49:55 UTC 2010
Citeren Jon Burgess <jburgess777 op googlemail.com>:
>> Several years ago on the linux-usb list, it was often pointed out that
>> the kernel was supposed to honor the wMaxPacketSize field, and
>> fragment the requests accordingly. While this was suggested for
>> performance reasons (fewer round trips between user and kernel space),
>> it should still hold true for less frequent transfers.
> In this case we are reading the data, I don't know if there is much the
> kernel can do to fragment this, I don't see any concept of an offset
> field when reading the report.
There is no need for an offset field. If you read/write the same
report again and the device will return/accept the next chunk of data.
The drawback here is that this most likely lead to a timeout after the
last available data has been read on the next read operation. We need
to deal with that.
Best regards, Arjen
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