[U-Boot] [PATCH 5/6] usb: Don't reset the USB hub a 2nd time

Stefan Roese
2016-03-11T06:43:07Z

On 10.03.2016 20:13, Hans de Goede wrote:
> Hi,
>
> On 10-03-16 16:50, Stefan Roese wrote:
>> Debugging has shown, that all USB hubs are being resetted twice while
>> USB scanning. This introduces additional delays and makes USB scanning
>> even more slow. Testing has shown that this 2nd USB hub reset doesn't
>> seem to be necessary.
>>
>> This patch now removes this 2nd USB hub reset if CONFIG_USB_FAST_SCAN
>> is defined. Resulting in faster USB scan time. Here the current
>> number:
>>
>> Without this patch:
>> => time usb start
>> starting USB...
>> USB0: USB EHCI 1.00
>> scanning bus 0 for devices... 9 USB Device(s) found
>>
>> time: 6.319 seconds
>>
>> With this patch:
>> => time usb start
>> starting USB...
>> USB0: USB EHCI 1.00
>> scanning bus 0 for devices... 9 USB Device(s) found
>>
>> time: 3.777 seconds
>>
>> So ~2.5 seconds of USB scanning time reduction.
>>
>> Again, this 2nd reset is only removed if CONFIG_USB_FAST_SCAN is
>> defined. Once more tests are done on multiple other platforms we
>> can decide to remove this 2nd reset completely.
>
> I see no reason to make the removal conditional, I believe that
> this is some relic workaround for likely long fixed bugs and
> we should just remove it completely (for v2016.07).

Thanks. I'll make this change unconditional in the next patch version
as well.

Thanks,
Stefan