erebion/coreboot
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

libpayload: usbhub: Don't clear PSC unless it was set

Browse source 
The current USB hub code always clears the port status change after
checking it, regardless of whether it was set in the first place. Since
this check runs on every poll, it might create a race condition where
the port status changes right between the GET_PORT_STATUS and the
CLEAR_FEATURE(C_PORT_CONNECT), thus clearing the statrus change flag
before it was ever read. Let's add one extra if() to avoid that possible
headache.

BUG=chrome-os-partner:21969
TEST=None

Change-Id: Idd46c2199dc6c240bd9ef068fbe70cccc88bac42
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/168098
This commit is contained in:
Julius Werner 2013-09-03 16:44:15 -07:00 • committed by chrome-internal-fetch
commit f7f6f008f7
1 changed files with 2 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

3
payloads/libpayload/drivers/usb/usbhub.c
View file

@ -48,7 +48,8 @@ usb_hub_port_status_changed(usbdev_t *const dev, const int port)
{
unsigned short buf[2] = { 0, 0 };
get_status (dev, port, DR_PORT, 4, buf);
clear_feature (dev, port, SEL_C_PORT_CONNECTION, DR_PORT);
if (buf[1] & PORT_CONNECTION)
clear_feature (dev, port, SEL_C_PORT_CONNECTION, DR_PORT);
return buf[1] & PORT_CONNECTION;
}