linux-kernel - Re: [PATCH v2 2/3] usb: gadget: f_midi: free usb request when done

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Message-ID: <20150924013807.GC10369@shlinux2>
Date:	Thu, 24 Sep 2015 09:38:08 +0800
From:	Peter Chen <peter.chen@...escale.com>
To:	"Felipe F. Tonello" <eu@...ipetonello.com>
CC:	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	Felipe Balbi <balbi@...com>,
	Andrzej Pietrasiewicz <andrzej.p@...sung.com>
Subject: Re: [PATCH v2 2/3] usb: gadget: f_midi: free usb request when done

On Wed, Sep 23, 2015 at 01:01:44PM +0100, Felipe F. Tonello wrote:
> req->actual == req->length means that there is no data left to enqueue,
> so free the request.
> 
> Signed-off-by: Felipe F. Tonello <eu@...ipetonello.com>
> ---
> 
> Changes in v2:
>  * Re enqueue not fully completed requests, instead of read ALSA buffers.
> 
>  drivers/usb/gadget/function/f_midi.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index edb84ca..62356cf 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -256,10 +256,12 @@ f_midi_complete(struct usb_ep *ep, struct usb_request *req)
>  			/* We received stuff. req is queued again, below */
>  			f_midi_handle_out_data(ep, req);
>  		} else if (ep == midi->in_ep) {
> -			/* Our transmit completed. See if there's more to go.
> -			 * f_midi_transmit eats req, don't queue it again. */
> -			f_midi_transmit(midi, req);
> -			return;
> +			/* Our transmit completed. If there is no more to go,
> +			   don't queue it again. */
> +			if (req->actual == req->length) {
> +				free_ep_req(ep, req);
> +				return;
> +			}

I find f_midi_transmit will judge if there are more data, if without
data, it will free the request.

Besides, does one trigger only do one transfer? Sorry, I can't make my
aplaymidi to receive data, probably due to hardware without midi
support?

root@...6qpsabreauto:~# aplaymidi
ALSA lib
/var/lib/jenkins/workspace/fido-3.14.28-X11-consolidated_new/temp_build_dir/build_all/tmp/work/cortexa9hf-vfp-neon-mx6qdl-poky-linux-gnueabi/alsa-lib/1.0.28-r0/alsa-lib-1.0.28/src/seq/seq_hw.c:457:(snd_seq_hw_open)
open /dev/snd/seq failed: No such file or directory
Cannot open sequencer - No such file or directory

-- 

Best Regards,
Peter Chen
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