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From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: Phillip Potter <phil@philpotter.co.uk>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Larry Finger <Larry.Finger@lwfinger.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"open list:STAGING SUBSYSTEM" <linux-staging@lists.linux.dev>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Pavel Skripkin <paskripkin@gmail.com>
Subject: Re: [PATCH 1/2] staging: r8188eu: Use usb_control_msg_recv/send() in usbctrl_vendorreq()
Date: Tue, 24 Aug 2021 12:38:20 +0200	[thread overview]
Message-ID: <1751314.Y7PUP2lcel@localhost.localdomain> (raw)
In-Reply-To: <50d40020-5b0e-4bb9-357b-3640a0f9e8c6@wanadoo.fr>

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
> 





  reply	other threads:[~2021-08-24 10:38 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 22:37 [PATCH 0/2] staging: r8188eu: Use new usb_control_msg_recv/send() Fabio M. De Francesco
2021-08-23 22:37 ` [PATCH 1/2] staging: r8188eu: Use usb_control_msg_recv/send() in usbctrl_vendorreq() Fabio M. De Francesco
2021-08-24  0:08   ` Phillip Potter
2021-08-24  0:31     ` Fabio M. De Francesco
2021-08-24  1:38       ` Fabio M. De Francesco
2021-08-24  2:01         ` Fabio M. De Francesco
2021-08-24  5:44           ` Christophe JAILLET
2021-08-24 10:38             ` Fabio M. De Francesco [this message]
2021-08-24 17:03               ` Christophe JAILLET
2021-08-24 21:59         ` Phillip Potter
2021-08-24  8:13   ` Pavel Skripkin
2021-08-24  8:53     ` Fabio M. De Francesco
2021-08-24 11:07       ` Pavel Skripkin
2021-08-24 12:01         ` Fabio M. De Francesco
2021-08-24 12:09           ` Pavel Skripkin
2021-08-24 14:55             ` Fabio M. De Francesco
2021-08-23 22:37 ` [PATCH 2/2] staging: r8188eu: Make some clean-ups " Fabio M. De Francesco
2021-08-24  0:10   ` Phillip Potter

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