Re: Use of USB_CTRL_SET_TIMEOUT & USB_CTRL_GET_TIMEOUT

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On Mon, Jun 20, 2016 at 7:19 PM, Felipe Balbi
<felipe.balbi@xxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> Muni Sekhar <munisekharrms@xxxxxxxxx> writes:
>>> Muni Sekhar <munisekharrms@xxxxxxxxx> writes:
>>>> Hi All,
>>>>
>>>> Usb.h file is having the below mentioned USB_CTRL_SET_TIMEOUT &
>>>> USB_CTRL_GET_TIMEOUT macros.
>>>>
>>>>
>>>>
>>>> /*
>>>>
>>>>  * timeouts, in milliseconds, used for sending/receiving control messages
>>>>
>>>>  * they typically complete within a few frames (msec) after they're issued
>>>>
>>>>  * USB identifies 5 second timeouts, maybe more in a few cases, and a few
>>>>
>>>>  * slow devices (like some MGE Ellipse UPSes) actually push that limit.
>>>>
>>>>  */
>>>>
>>>> #define USB_CTRL_GET_TIMEOUT    5000
>>>>
>>>> #define USB_CTRL_SET_TIMEOUT    5000
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Does the above mentioned timeouts will vary based on the packet length
>>>> of control transfers (8, 16, 32 or 64 bytes)?
>>>>
>>>>
>>>>
>>>> I do have a USB Bluetooth device and it exposes the control endpoint
>>>> for sending HCI commands.
>>>>
>>>>
>>>>
>>>> I’m not sure what will be the good value for the
>>>> usb_control_msg()timeout for sending HCI commands, will it be safe to
>>>> use USB_CTRL_SET_TIMEOUT?
>>>
>>> why wouldn't it? If your device doesn't respond to a control message in
>>> 5 seconds, then you should really get that FW fixed or change your
>>> device to something that works. 5 seconds to transfer a few bytes is a
>>> really long time. Even for low-speed pipes (1.5Mbps), you can transfer
>>> 960 kiB in 5 seconds if you saturate the bus. How big are your HCI
>>> commands?
>>
>> HCI Command Packets with up to maximum of 255 bytes of data.
>
> then 5s is more than enough for you ;-)

What usually triggers the usb_control_msg() call to return? Is it just
an acknowledgement from the device that the command has been received?

>
> --
> balbi



-- 
Thanks,
Sekhar
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