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>
Regards,
Hans
Signed-off-by: Stefan Roese <s...@denx.de>
Cc: Simon Glass <s...@chromium.org>
Cc: Hans de Goede <hdego...@redhat.com>
Cc: Stephen Warren <swar...@nvidia.com>
Cc: Marek Vasut <ma...@denx.de>
---
common/usb_hub.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/common/usb_hub.c b/common/usb_hub.c
index 10fdd3c..660f4f4 100644
--- a/common/usb_hub.c
+++ b/common/usb_hub.c
@@ -275,7 +275,9 @@ int usb_hub_port_connect_change(struct usb_device *dev, int
port)
if (!(portstatus & USB_PORT_STAT_CONNECTION))
return -ENOTCONN;
}
+#if !defined(CONFIG_USB_FAST_SCAN)
mdelay(200);
+#endif
/* Reset the port */
ret = legacy_hub_port_reset(dev, port, &portstatus);
@@ -285,7 +287,9 @@ int usb_hub_port_connect_change(struct usb_device *dev, int
port)
return ret;
}
+#if !defined(CONFIG_USB_FAST_SCAN)
mdelay(200);
+#endif
switch (portstatus & USB_PORT_STAT_SPEED_MASK) {
case USB_PORT_STAT_SUPER_SPEED:
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