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Subject: Re: [PATCH] usb:cdns3: Fix for CV CH9 running with g_zero driver.
To:     Pawel Laszczak <pawell@cadence.com>,
        Felipe Balbi <felipe.balbi@linux.intel.com>,
        Peter Chen <peter.chen@nxp.com>
CC:     "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "jbergsagel@ti.com" <jbergsagel@ti.com>,
        "nsekhar@ti.com" <nsekhar@ti.com>, "nm@ti.com" <nm@ti.com>,
        Suresh Punnoose <sureshp@cadence.com>,
        Rahul Kumar <kurahul@cadence.com>
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From:   Roger Quadros <rogerq@ti.com>
Message-ID: <80047a82-4b01-8f54-7efa-c32f696ced43@ti.com>
Date:   Wed, 9 Oct 2019 16:50:48 +0300
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Pawel,

On 09/10/2019 06:58, Pawel Laszczak wrote:
> Hi,
> 
>>
>> Hi,
>>
>> Peter Chen <peter.chen@nxp.com> writes:
>>> On 19-10-07 07:39:11, Pawel Laszczak wrote:
>>>> Patch fixes issue with Halt Endnpoint Test observed
>>>
>>> %s/Endnpoint/Endpoint
>>>
>>>>
>>>> during using g_zero
>>>> driver as DUT. Bug occurred only on some testing board.
>>>
>>> g_zero is legacy, please use configfs function source_sink or loopback
>>> instead.
>>
>> We still want fixes for those ;-)
> 
> So, if my understanding is correct in new production systems
> using legacy gadget drivers is not recommended and we are not going to fix
> any more bugs there.

We can't really control who uses what. So we need to support legacy
drivers as well.

The issue detected by using g_zero is a controller driver issue and not an
issue with g_zero itself.

cheers,
-roger

> 
> The legacy gadget drivers remains in the kernel only to support the old
> products.
> 
> So because we introduce new driver we should not worry  about legacy
> gadget drivers.
> 
> Is my understanding correct ?
> 
> pawell
>   
>>
>>>> Endpoint can defer transition to Halted state if endpoint has pending
>>>> requests.
>>>
>>> The implementation of halt handling is a little complicated, you may
>>> consider return -EAGAIN for functional stall through usb_ep_set_halt
>>> from function driver if the requests are pending, it doesn't need to
>>> defer such kinds of functional stall.
>>
>> -EAGAIN, IIRC is only supposed to be used for IN endpoint stalls.
>>
>> --
>> balbi

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