On 8/31/2016 12:47 PM, Felipe Balbi wrote:
>
> Hi John,
>
> John Youn <John.Youn@xxxxxxxxxxxx> writes:
>> On 8/31/2016 2:38 AM, Felipe Balbi wrote:
>>> If we don't know what are the actual U1/U2 exit
>>> latencies from the UDC, we're better off using
>>> maximum latencies as default. This should avoid
>>> any problems with too frequent U1/U2 entry.
>>>
>>> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
>>> ---
>>> include/linux/usb/gadget.h | 12 ++++++++++--
>>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
>>> index 3667d667cab1..20cb590c658e 100644
>>> --- a/include/linux/usb/gadget.h
>>> +++ b/include/linux/usb/gadget.h
>>> @@ -276,11 +276,19 @@ static inline void usb_ep_fifo_flush(struct usb_ep *ep)
>>>
>>> /*-------------------------------------------------------------------------*/
>>>
>>> +/**
>>> + * struct usb_dcd_config_params - Default U1/U2 exit latencies
>>> + * @bU1DevExitLat: U1 Exit Latency in us
>>> + * @bU2DevExitLat: U2 Exit Latency in us
>>> + *
>>> + * Note that we will be setting U1/U2 exit latencies to their maximum
>>> + * by default if no value is passed by the UDC Driver.
>>> + */
>>> struct usb_dcd_config_params {
>>> __u8 bU1DevExitLat; /* U1 Device exit Latency */
>>> -#define USB_DEFAULT_U1_DEV_EXIT_LAT 0x01 /* Less then 1 microsec */
>>> +#define USB_DEFAULT_U1_DEV_EXIT_LAT 10 /* us */
>>> __le16 wU2DevExitLat; /* U2 Device exit Latency */
>>> -#define USB_DEFAULT_U2_DEV_EXIT_LAT 0x1F4 /* Less then 500 microsec */
>>> +#define USB_DEFAULT_U2_DEV_EXIT_LAT 2047 /* us */
>>> };
>>>
>>>
>>>
>>
>> Hi Felipe,
>>
>> Speaking of this, how would you feel about adding module parameters in
>> the dwc3-pci to set these? And we also have several more settings in
>> our internal tree that we need for IP validation and debugging.
>>
>> As you know the IP is highly configurable, and we do much of the
>> testing against these configurations via software settings. And our
>> validation platform is not a typical platform. Basically we have a
>> single platform, but the instantiated IP and PHY could be configured
>> in any way so it could need different values passed in for
>> testing. Like the U1/U2 exit latencies, LPM NYET threshold, HIRD,
>> USB2/3 SUSPHY, LPM sleep mode, GFLADJ, etc.
>>
>> And some things that are automatically detected we need to restrict or
>> disable to get full coverage. Such as disabling U1/U2 and LPM, maximum
>> speed, dr_mode, NUMP, RX thresholding, RX thresholding packet count.
>>
>> I know module parameters are typically frowned upon so do you
>> recommend another approach?
>
> I completely understand the situation. Module parameters are, well,
> rather unsophisticated. FPGA validation is, however, a 'peculiar' use
> case.
>
> I want to avoid module parameters as much as possible, but apart from
> module parameters, the only thing I can think of is a specific
> sub-directory on debugfs which only gets compile if EXPERT &&
> DWC3_VALIDATION_MODE or whatever.
>
> Would debugfs work for you? The only problem is for things which get
> discovered during probe()
Yes that's the problem, otherwise I'd be fine with debugfs. Almost
everything we need is initialized on probe. I thought of maybe
refactoring the dwc3 code so that this doesn't have to happen on probe
and we can trigger a "module reset" or something. But that is not
exactly clean either.
Regards,
John
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