From 28b48aa69b55a983226edf2ea616f33cd4b959e2 Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Mon, 28 Apr 2014 16:04:24 -0700 Subject: [PATCH] libpayload: usb: Try to avoid reusing device addresses We recently changed the USB stack to detach devices aggressively that we don't intend to use. This alone is not really a problem, but it exarcerbates the fact that our device detachment itself is not very good. We destroy any local info about the device, but we don't properly disable the offending port. The device keeps thinking that it's active, and if we later try to reuse that device address for another device things become confused. The real fix would be to properly disable all ports that we don't intend to use. Unfortunately, this isn't really possible in our current device/hub polymorphism structure, and I don't want to hack a new disable_port() callback into usbdev_t that really doesn't belong there. We will only be able to fix this cleanly after we ported all root hubs to the generic_hub interface. Until then, an easy workaround is to just avoid reusing addresses as long as possible. This is firmware, so the chance that we'll ever run through 127 devices is really small in practice. Even if we ever fix the underlying issue, it's probably a smart precaution to keep. BRANCH=nyan,rambi BUG=chrome-os-partner:28328 TEST=Boot from a hub that has an "unknown" device in an earlier port than the stick you want to boot from, make sure you can still boot. Change-Id: I9b522dd8cbcd441e8c3b8781fcecd2effa0f23ee Signed-off-by: Julius Werner Reviewed-on: https://chromium-review.googlesource.com/197420 Reviewed-by: Shawn Nematbakhsh Reviewed-by: David Hendricks --- payloads/libpayload/drivers/usb/usb.c | 14 +++++++++++--- payloads/libpayload/include/usb/usb.h | 1 + 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/payloads/libpayload/drivers/usb/usb.c b/payloads/libpayload/drivers/usb/usb.c index 2d91cbb07a..d45cff2ab6 100644 --- a/payloads/libpayload/drivers/usb/usb.c +++ b/payloads/libpayload/drivers/usb/usb.c @@ -206,10 +206,18 @@ clear_stall (endpoint_t *ep) static int get_free_address (hci_t *controller) { - int i; - for (i = 1; i < 128; i++) { - if (controller->devices[i] == 0) + int i = controller->latest_address + 1; + for (; i != controller->latest_address; i++) { + if (i >= ARRAY_SIZE(controller->devices) || i < 1) { + usb_debug("WARNING: Device addresses for controller %#x" + " wrapped around!\n", controller->reg_base); + i = 0; + continue; + } + if (controller->devices[i] == 0) { + controller->latest_address = i; return i; + } } usb_debug ("no free address found\n"); return -1; // no free address diff --git a/payloads/libpayload/include/usb/usb.h b/payloads/libpayload/include/usb/usb.h index bb0058dfe0..b2137a534c 100644 --- a/payloads/libpayload/include/usb/usb.h +++ b/payloads/libpayload/include/usb/usb.h @@ -212,6 +212,7 @@ struct usbdev_hc { hci_t *next; u32 reg_base; hc_type type; + int latest_address; usbdev_t *devices[128]; // dev 0 is root hub, 127 is last addressable /* start(): Resume operation. */