linux-kernel - Re: [PATCH] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize

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Message-ID: <87lh1ci7tt.fsf@linux.intel.com>
Date:	Fri, 08 Jul 2016 16:21:34 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	Baolin Wang <baolin.wang@...aro.org>
Cc:	gregkh@...uxfoundation.org, eu@...ipetonello.com,
	mina86@...a86.com, r.baldyga@...sung.com, dan.carpenter@...cle.com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	broonie@...nel.org, baolin.wang@...aro.org
Subject: Re: [PATCH] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize


Hi,

Baolin Wang <baolin.wang@...aro.org> writes:
> Some gadget device (such as dwc3 gadget) requires quirk_ep_out_aligned_size
> attribute, which means it need to align the request buffer's size to an ep's
> maxpacketsize.
>
> Thus we add usb_ep_align_maybe() function to check if it is need to align
> the request buffer's size to an ep's maxpacketsize.
>
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
>  drivers/usb/gadget/function/f_midi.c |   18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index 58fc199..2e3f11e 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -328,7 +328,7 @@ static int f_midi_start_ep(struct f_midi *midi,
>  static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
>  {
>  	struct f_midi *midi = func_to_midi(f);
> -	unsigned i;
> +	unsigned i, length;
>  	int err;
>  
>  	/* we only set alt for MIDIStreaming interface */
> @@ -345,9 +345,11 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
>  
>  	/* pre-allocate write usb requests to use on f_midi_transmit. */
>  	while (kfifo_avail(&midi->in_req_fifo)) {
> -		struct usb_request *req =
> -			midi_alloc_ep_req(midi->in_ep, midi->buflen);
> +		struct usb_request *req;
>  
> +		length = usb_ep_align_maybe(midi->gadget, midi->in_ep,
> +					    midi->buflen);

this is not needed for in_ep, only out_ep, right?

> +		req = midi_alloc_ep_req(midi->in_ep, length);
>  		if (req == NULL)
>  			return -ENOMEM;
>  
> @@ -359,10 +361,12 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
>  
>  	/* allocate a bunch of read buffers and queue them all at once. */
>  	for (i = 0; i < midi->qlen && err == 0; i++) {
> -		struct usb_request *req =
> -			midi_alloc_ep_req(midi->out_ep,
> -				max_t(unsigned, midi->buflen,
> -					bulk_out_desc.wMaxPacketSize));
> +		struct usb_request *req;
> +
> +		length = usb_ep_align_maybe(midi->gadget, midi->out_ep,
> +					    midi->buflen);

after calling usb_ep_align_maybe()...

> +		req = midi_alloc_ep_req(midi->out_ep,
> +			max_t(unsigned, length, bulk_out_desc.wMaxPacketSize));

... max_t() is pointless. length will *always* >= wMaxPacketSize.

-- 
balbi

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