[U-Boot] [PATCH v4 3/4] usb: Don't reset the USB hub a 2nd time

Stefan Roese
2016-03-15T09:46:45Z

Debugging has shown, that all USB hubs are being reset 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. Resulting in faster USB
scan time. Here the current numbers:

Without this patch:
=> time usb start
starting USB...
USB0: USB EHCI 1.00
scanning bus 0 for devices... 9 USB Device(s) found

time: 24.003 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: 20.392 seconds

So ~3.6 seconds of USB scanning time reduction.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Cc: Marek Vasut <marex@denx.de>

---

Changes in v4:
- Minor rewording / fixes of the commit text
- Add Acked-by from Hans

Changes in v3: None
Changes in v2:
- Make this change unconditional
- Add Tested-by from Stephen

common/usb.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/common/usb.c b/common/usb.c
index c7b8b0e..45a5a0f 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -919,19 +919,8 @@ __weak int usb_alloc_device(struct usb_device *udev)

static int usb_hub_port_reset(struct usb_device *dev, struct usb_device *hub)
{
- if (hub) {
- unsigned short portstatus;
- int err;
-
- /* reset the port for the second time */
- err = legacy_hub_port_reset(hub, dev->portnr - 1, &portstatus);
- if (err < 0) {
- printf("\n Couldn't reset port %i\n", dev->portnr);
- return err;
- }
- } else {
+ if (!hub)
usb_reset_root_port(dev);
- }

return 0;
}
--
2.7.3