[3/3] usb: dwc3: Support option to disable USB2 LPM

[Roger Quadros <rogerq@ti.com>]

Thinh,

On 12/11/18 07:29, Thinh Nguyen wrote:
> Hi Roger,
> 
> On 11/9/2018 3:58 AM, Roger Quadros wrote:
>> Hi,
>>
>> On 08/11/18 04:10, Thinh Nguyen wrote:
>>> Support the option to disable USB2 LPM. Set xhci "usb2-lpm-disable"
>>> property via "snps,usb2-lpm-disable" property.
>>>
>>> Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
>>> ---
>>>  drivers/usb/dwc3/core.c | 2 ++
>>>  drivers/usb/dwc3/core.h | 2 ++
>>>  drivers/usb/dwc3/host.c | 5 ++++-
>>>  3 files changed, 8 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> index a4068a7b95dd..f6b80a545a78 100644
>>> --- a/drivers/usb/dwc3/core.c
>>> +++ b/drivers/usb/dwc3/core.c
>>> @@ -1248,6 +1248,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>>>  				&hird_threshold);
>>>  	dwc->usb3_lpm_capable = device_property_read_bool(dev,
>>>  				"snps,usb3_lpm_capable");
>>> +	dwc->usb2_lpm_disable = device_property_read_bool(dev,
>>> +				"snps,usb2-lpm-disable");
>> Can we use the same logic as usb3_lpm instead?
>> i.e. enable USB2 LPM only if "snps,usb2_lpm_capable" is present in DT.
>> This is because older platforms that are not tested for usb2 lpm
>> might break if you enable it by default.
> 
> I follow the same logic as usb-xhci property. The usb2-lpm-disable
> property from xHCI has been around for awhile. Do you suggest to change
> the property for xHCI then?

No.
I see it now that you are just setting the XHCI property and not
doing any change in the dwc3 functionality itself.
I think your patch is correct.

>> Also can we have some consistency in usage of '-' vs '_'?
> Right.. I agree. I've been using '-' as it is the preferred syntax as
> most of the properties, but some old properties use '_'. Do you have any
> suggestion?

I'd keep it consistent to "snps,usb3_lpm_capable" so we avoid mistakes
when writing the DT.
Felipe?

cheers,
-roger