On Wednesday 15 June 2005 3:30 am, Jochen Karrer wrote:
>
> le16_to_cpus(&hub->descriptor->wHubCharacteristics); /* This triggers two
> alignment exceptions */
> if (hub->descriptor->wHubCharacteristics & HUB_CHAR_COMPOUND) { /* This
> works */
This is a good example of a place where <asm/unaligned.h> helps ...
modulo issues about when GCC discards the "packed" attribute!
On the other hand, the internals of the hub driver would seem to be
a place that missed out on the updates making USB code leave all the
descriptors in USB-standard (little endian) byte order.
A better fix in this case might be to leave the byteorder alone and
just
if (...->wHubCharacteristics & cpu_to_le16(HUB_CHAR_COMPOUND)) {
...
}
Feel free to take up the GCC query on GCC lists, but I think this
bit of USB code should just be updated to follow the same policy
as the other USB code: don't byteswap the in-memory desriptors.
I notice that in "hub.h" that field is declared "__u16" instead of
being "__le16" as it should be ... make that change and "sparse"
will remind you of all the places that need to change. (Or
maybe it's "sparse -Wbitwise"; have the toplevel makefile do that
for you.)
- Dave
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