linux-kernel - Re: [PATCH] usb: dwc3: gadget: Fix failure to detect end of transfer

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Message-ID: <0c183570-38cc-c27e-f5ab-606387a88dff@linaro.org>
Date:   Tue, 31 Dec 2019 00:21:29 +0000
From:   Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     balbi@...nel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: dwc3: gadget: Fix failure to detect end of transfer

On 31/12/2019 00:05, Bryan O'Donoghue wrote:
> On 30/12/2019 18:57, Greg KH wrote:
>> On Mon, Dec 30, 2019 at 04:13:21PM +0000, Bryan O'Donoghue wrote:
>>> A recent bugfix 8c7d4b7b3d43 ("usb: dwc3: gadget: Fix logical 
>>> condition")
>>> correctly fixes a logical error in the gadget driver but, exposes a 
>>> further
>>> bug in determining when a transfer has completed.
>>>
>>> Prior to 8c7d4b7b3d43 we were calling dwc3_gadget_giveback() when we
>>> shouldn't have been. Afer this change the below test fails to 
>>> complete on
>>> my hardware.
>>>
>>> Host:
>>> echo "host" > /dev/ttyACM0
>>>
>>> Device:
>>> cat < /dev/ttyGS0
>>>
>>> This is caused by the driver incorrectly detecting end of transfer, a
>>> problem that had previous been masked by the continuous calling of
>>> dwc3_gadget_giveback() prior to 8c7d4b7b3d43.
>>>
>>> Remediate by making the test <= instead of ==
>>>
>>> Fixes: e0c42ce590fe ("usb: dwc3: gadget: simplify IOC handling")
>>>
>>> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
>>> ---
>>>   drivers/usb/dwc3/gadget.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> I think this patch:
>>     https://lore.kernel.org/linux-usb/ac5a3593a94fdaa3d92e6352356b5f7a01ccdc7c.1576291140.git.thinhn@synopsys.com/ 
>>
>>
>> should fix this issue instead, right?
>>
>> If not, do I need to include both of these?
> 
> Yep, works fine in isolation.
> 

I don't have that in my inbox anywhere - not sure why, would have saved 
me 1/2 a day of work.

Anyway, please feel free to add my

Tested-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org> to Thinh's patch

---
bod