On Tuesday, August 24, 2021 7:44:40 AM CEST Christophe JAILLET wrote:
> Le 24/08/2021 à 04:01, Fabio M. De Francesco a écrit :
> > On Tuesday, August 24, 2021 3:38:03 AM CEST Fabio M. De Francesco wrote:
> >> I think that I've inadvertently switched the order by which usb_control_msg_send()
> >> and memcpy() are called. I'm very sorry for not doing my tests, but (as I had said
> >> before) at the moment I don't have my device with me.
> >
> > No, I did not switch them. There must be something else...
> > Sorry for the noise.
> >
> > Fabio
> >
>
> Hi,
>
> 'usb_control_msg_recv()' looks like:
>
> int usb_control_msg_recv(struct usb_device *dev, __u8 endpoint, ...)
> {
> unsigned int pipe = usb_rcvctrlpipe(dev, endpoint);
> ...
> ret = usb_control_msg(dev, pipe, ...);
>
>
> 'usb_control_msg()' looks like:
> int usb_control_msg(struct usb_device *dev, unsigned int pipe, ...)
> {
>
> The difference is that one expect an 'endpoint' (and compute the pipe
> from it), and the other expect a 'pipe'.
Hi Christophe,
Yes, correct. That's why I changed the type of 'pipe' from "unsigned int"
to "u8". I also saw that usb_control_msg_recv/send take care of calling
usb_rcvctrpipe() and usb_sndctrlpipe(); so, in my patch I deleted
those calls.
Not related to my patch... why Linux has u8 and __u8? What are the
different use cases they are meant for?
> Also, in your code, 'pipe' looks un-initialized.
Oh yes, good catch. Thanks!
> So, my guess is that you should rename 'pipe' into 'endpoint' (to keep
> the semantic),
> have "endpoint = 0;" somewhere and pass it to
> usb_control_msg_{recv|send}.
> Or just remove 'pipe' and pass an explicit 0 directly.
I've just seen that in other drivers the code passes an explicit 0.
So, also according to your suggestion, I'll remove "pipe/endpoint".
> Not sure it is enough, but it looks like a difference between before and
> after your patch.
Since I cannot see other issues, I'm about to fix the code as said above and
then submit a v2 series.
Your 2c are worth much more than how much you think :)
Thanks very much,
Fabio
> just my 2c,
> CJ
>
