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SubjectRe: [PATCH] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize
On 8 July 2016 at 21:21, Felipe Balbi <balbi@kernel.org> wrote:
>
> Hi,
>
> Baolin Wang <baolin.wang@linaro.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@linaro.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?

Yes. You are 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.

It is not. If the gadget device dose not require
quirk_ep_out_aligned_size, then the lengh may be <= wMaxPacketSize.

--
Baolin.wang
Best Regards

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