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 <hdego...@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
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