Re: [PATCH 4/4] usb: musb: gadget: do read_fifo for non zero data only

[Sergei Shtylyov <sshtylyov@xxxxxxxxxx>]

On 07/19/2012 03:22 PM, Gupta, Ajay Kumar wrote:

>>> There is no need to call read_fifo for zero byte length.

>>     The same as there's no need to write, and not only here?

> Yes, it applies to write also but seems write is taken care
> for zero byte length. 

   Frankly speaking, I don't see it. And what about non-0 endpoints?

>>> Signed-off-by: Ajay Kumar Gupta <ajay.gupta@xxxxxx>
>>> ---
>>>   drivers/usb/musb/musb_gadget_ep0.c |    6 ++++--
>>>   1 files changed, 4 insertions(+), 2 deletions(-)

>>> diff --git a/drivers/usb/musb/musb_gadget_ep0.c
>> b/drivers/usb/musb/musb_gadget_ep0.c
>>> index e40d764..d762ddb 100644
>>> --- a/drivers/usb/musb/musb_gadget_ep0.c
>>> +++ b/drivers/usb/musb/musb_gadget_ep0.c
>>> @@ -505,8 +505,10 @@ static void ep0_rxstate(struct musb *musb)
>>>   			req->status = -EOVERFLOW;
>>>   			count = len;
>>>   		}
>>> -		musb_read_fifo(&musb->endpoints[0], count, buf);
>>> -		req->actual += count;
>>> +		if (count) {
>>> +			musb_read_fifo(&musb->endpoints[0], count, buf);
>>> +			req->actual += count;
>>> +		}

>>     Does it save much?

> We do save some instruction and that's good to have.

   Wouldn't it be better to check for zero count inside musb_{read|write}_fifo()
though?

WBR, Sergei

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