[U-Boot] [PATCH 2/6] usb: Remove 200 ms delay in usb_hub_port_connect_change()

[Stefan Roese]

On 10.03.2016 19:55, Hans de Goede wrote:
> Hi,
>
> On 10-03-16 16:50, Stefan Roese wrote:
>> This patch removes 2 mdelay(200) calls from
>> usb_hub_port_connect_change().
>> These delays don't seem to be necessary. At least not in my tests. Here
>> the number for a custom x86 Bay Trail board (not in mainline yet) with
>> a quite large and complex USB hub infrastructure.
>>
>> Without this patch:
>> starting USB...
>> USB0:   USB EHCI 1.00
>> scanning bus 0 for devices... 9 USB Device(s) found
>>
>> time: 28.415 seconds
>>
>> With this patch:
>> starting USB...
>> USB0:   USB EHCI 1.00
>> scanning bus 0 for devices... 9 USB Device(s) found
>>
>> time: 24.811 seconds
>>
>> So ~3.5 seconds of USB scanning time reduction.
>>
>> These mdelay calls are removed if CONFIG_USB_FAST_SCAN is defined. They
>> are not removed per default yet. It would be good to test with this
>> option enabled on many other boards. And once we have a good testing
>> base we can decide to remove these delays completely, including this
>> macro.
>
> There indeed is no reason at all to delay before the reset and the kernel
> does not wait with checking the USB_PORT_STAT_SPEED_MASK once the
> reset completes, so I see no reason why we should:
>
> Acked-by: Hans de Goede <hdegoede at redhat.com>

Thanks. I'll remove the #if !defined(CONFIG_USB_FAST_SCAN) to make
this change default in the next patchset version.

Thanks,
Stefan