Re: [EXT] Re: [PATCH 1/1] usb: gadget: call usb_gadget_check_config() to verify UDC capability

[Roger Quadros]

On 29/06/2023 06:40, Frank Li wrote:
> 
> 
>> -----Original Message-----
>> From: Roger Quadros <rogerq@xxxxxxxxxx>
>> Sent: Wednesday, June 28, 2023 10:23 PM
>> To: Frank Li <frank.li@xxxxxxx>; r-gunasekaran@xxxxxx; imx@xxxxxxxxxxxxxxx;
>> Jun Li <jun.li@xxxxxxx>; Greg Kroah-Hartman
>> <gregkh@xxxxxxxxxxxxxxxxxxx>; Elson Roy Serrao
>> <quic_eserrao@xxxxxxxxxxx>; Thinh Nguyen
>> <Thinh.Nguyen@xxxxxxxxxxxx>; Andy Shevchenko
>> <andriy.shevchenko@xxxxxxxxxxxxxxx>; Jó Ágila Bitsch <jgilab@xxxxxxxxx>;
>> Prashanth K <quic_prashk@xxxxxxxxxxx>; Peter Chen
>> <peter.chen@xxxxxxxxxx>; open list:USB SUBSYSTEM <linux-
>> usb@xxxxxxxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx>
>> Subject: [EXT] Re: [PATCH 1/1] usb: gadget: call usb_gadget_check_config()
>> to verify UDC capability
>>
>> Caution: This is an external email. Please take care when clicking links or
>> opening attachments. When in doubt, report the message using the 'Report
>> this email' button
>>
>>
>> On 29/06/2023 03:54, Frank Li wrote:
>>> The legacy gadget driver omitted calling usb_gadget_check_config()
>>> to ensure that the USB device controller (UDC) has adequate resources,
>>> including sufficient endpoint numbers and types, to support the given
>>> configuration.
>>>
>>> Previously, usb_add_config() was solely invoked by the legacy gadget
>>> driver. Adds the necessary usb_gadget_check_config() after the bind()
>>> operation to fix the issue.
>>
>> You have only fixed composite.c. Not all gadget drivers use composite.c
>> so it will be still broken for them.
>>
>> Please also add default sane configuration in CDNS3 so it works even
>> if usb_gadget_check_config() is not invoked.
> 
> Which one was not call usb_add_config()?
> DWC3 also use
>  .check_config		= dwc3_gadget_check_config, 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/dwc3/gadget.c 

I meant gadget drivers not UDC drivers.

e.g.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/gadget/legacy/dbgp.c

> 
> I think it is not correct by assume UDC can support specific config
> at gadget function driver. 
> Add default value of CDNS3 actually hidden potential problem. 
> 
> I don't suggest it before fixed hidden potential problem. 
> 
> Frank  
> 
>>
>>>
>>> Fixes: dce49449e04f ("usb: cdns3: allocate TX FIFO size according to
>> composite EP number")
>>> Reported-by: Ravi Gunasekaran <r-gunasekaran@xxxxxx>
>>> Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
>>> ---
>>>  drivers/usb/gadget/composite.c | 4 ++++
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/usb/gadget/composite.c
>> b/drivers/usb/gadget/composite.c
>>> index 1b3489149e5e..dd9b90481b4c 100644
>>> --- a/drivers/usb/gadget/composite.c
>>> +++ b/drivers/usb/gadget/composite.c
>>> @@ -1125,6 +1125,10 @@ int usb_add_config(struct usb_composite_dev
>> *cdev,
>>>               goto done;
>>>
>>>       status = bind(config);
>>> +
>>> +     if (status == 0)
>>> +             status = usb_gadget_check_config(cdev->gadget);
>>> +
>>>       if (status < 0) {
>>>               while (!list_empty(&config->functions)) {
>>>                       struct usb_function             *f;
>>
>> --
>> cheers,
>> -roger

-- 
cheers,
-roger