[U-Boot] [PATCH v2 0/4] usb: Reduce USB scanning time

[Stephen Warren]

On 03/11/2016 07:55 AM, Stefan Roese wrote:
>
> My current x86 platform (Bay Trail, not in mainline yet) has a quite
> complex USB infrastructure with many USB hubs. Here the USB scan takes
> an incredible huge amount of time:
>
> starting USB...
> USB0:   USB EHCI 1.00
> scanning bus 0 for devices... 9 USB Device(s) found
>
> time: 28.415 seconds
>
> This is of course not acceptable on platforms, where USB needs to get
> scanned at every bootup. As this increases the bootup time of this
> device by nearly 30 seconds!
>
> This patch series greatly reduces the USB scanning time. This is done
> by multiple means:
>
> - Remove or reduce delays and timeouts
> - Remove a 2nd reset of the USB hubs
> - Change USB port timeout handling and introduce quasi parallel USB
>    port scanning
>
> As a result, the USB scanning time is greatly reduced:
>
> starting USB...
> USB0:   USB EHCI 1.00
> scanning bus 0 for devices... 9 USB Device(s) found
>
> time: 4.606 seconds
>
> As you can see, the time is reduced from 28.4 to 4.6 seconds!
>
> Please find more details to the changes in the patch description.
>
> Testing and comments welcome!

The series,
Tested-by: Stephen Warren <swarren at nvidia.com>
(same set of tests as last time)