From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takashi Iwai <tiwai@suse.de>
Subject: Re: usb audio callback questions.
Date: Mon, 07 Jul 2003 12:26:39 +0200
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To: James Courtier-Dutton <James@superbug.demon.co.uk>
Cc: alsa-devel <alsa-devel@lists.sourceforge.net>
List-Id: alsa-devel@alsa-project.org

At Sun, 06 Jul 2003 14:21:52 +0100,
James Courtier-Dutton wrote:
> 
> I have a question regarding the callbacks in the usbaudio.c driver.
> The callback is defined as: -
> 
> /*
>   * complete callback from data urb
>   */
> static void snd_complete_urb(struct urb *urb, struct pt_regs *regs)
> 
> 
> The callback is set up with: -
> u->urb->complete = snd_usb_complete_callback(snd_complete_urb);
> 
> The issue I have is that urb->complete is of type: -
> struct urb;
> typedef void (*usb_complete_t)(struct urb *);
> 
> struct urb
> {
> <snip>
>          usb_complete_t complete;        // pointer to completion routine
> <snip>
> };
> 
> So, why is the "struct pt_regs *regs" there ?
> I would think that
> static void snd_complete_urb(struct urb *urb, struct pt_regs *regs)
> should change to
> static void snd_complete_urb(struct urb *urb)

the second argument is added in the 2.5 USB-driver stack.
we have a (rather complex) wrapper for that, to compile the same
source both for 2.4 and 2.5 (even 2.2) kernels.
yeah, it needs more clean up...


Takashi


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