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

[Michal Nazarewicz <mina86@mina86.com>]

On Thu, Jul 07 2016, Baolin Wang wrote:
> 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@linaro.org>

Acked-by: Michal Nazarewicz <mina86@mina86.com>

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

Perhaps:

+		length = midi->buflen < bulk_out_desc.wMaxPacketSize
+			? bulk_out_desc.wMaxPacketSize
+			: usb_ep_align_maybe(midi->gadget, midi->out_ep,
+					     midi->buflen);
+		req = midi_alloc_ep_req(midi->out_ep, length);

I find it somewhat cleaner.  Up to you.

>  		if (req == NULL)
>  			return -ENOMEM;
>  

-- 
Best regards
ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ
«If at first you don’t succeed, give up skydiving»