Hi Sergei,

Sergei Shtylyov wrote:
quoted text
> Hello.
> 
> Holger brunck wrote:
> 
>> From: Stefan Bigler <stefan.bigler@keymile.com>
> 
>> Some usb serial host drivers expect a short packet before they forward
>> the data to the application. This is caused by them trying to read more
>> than one packet at a time. So when the gadget sends an exact multiple
>> of the maximum packet size, it should append a zero-length packet.
>> The gadget driver for fsl_qe was not handling this case correctly.
>> This patch adds sending of a null packet if it is the last packet of
>> a frame and the request length is USB_EP0_MAX_SIZE (64 Byte).
> 
>> See also commit 2e25134122c25ebb0679b4bbd536fb46c669f9d7
> 
>    Linus has asked to also specify the commit summary in parens.
> 

Ok I will do this if the patch is with regards to its content ok.

quoted text
>> Signed-off-by: Stefan Bigler <stefan.bigler@keymile.com>
>> Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
>> Cc: Li Yang <leoli@freescale.com>
>> Cc: David Brownell <dbrownell@users.sourceforge.net>
> 
>> ---
>>  drivers/usb/gadget/fsl_qe_udc.c |    3 +++
>>  1 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/fsl_qe_udc.c
>> b/drivers/usb/gadget/fsl_qe_udc.c
>> index 7881f12..279454a 100644
>> --- a/drivers/usb/gadget/fsl_qe_udc.c
>> +++ b/drivers/usb/gadget/fsl_qe_udc.c
>> @@ -1229,6 +1229,9 @@ static int frame_create_tx(struct qe_ep *ep,
>> struct qe_frame *frame)
>>         else
>>                 reval = sendnulldata(ep, frame, 0);
> 
>    No, really you shouldn't send null data in every case when
> req->req.length - ep->sent <= 0, only if req->req.length == 0 or
> req->req.zero == 1...
> 

Hm, yes this piece of code looks a bit odd to me too. And I did not understand
what it should solve. But I let it untouched, because the bug my patch should
fix is in my eyes a different topic.

quoted text
>> +       if (req->req.zero && (req->req.length == USB_EP0_MAX_SIZE))
> 
>    Not (req->req.length % USB_EP0_MAX_SIZE == 0)? Also, you should
> probably check that ep->sent == req->req.length here...
> 

No not (req->req.length % USB_EP0_MAX_SIZE == 0), because the nulldata which is
missing should only be send if it is the last packet of a frame and not every
time a 64byte packet is send.

Best regards
Holger

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