The detection function of the EHCI PCI controller was really cryptic,
add a beefy comment and clean the portion of the code up a bit. No
change in the logic of the code.
Signed-off-by: Marek Vasut <ma...@denx.de>
Cc: Simon Glass <s...@chromium.org>
---
drivers/usb/host/ehci-pci.c | 28 +++++++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 7a1ffe5..991b199 100644
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -54,9 +54,31 @@ static pci_dev_t ehci_find_class(int index)
bdf += PCI_BDF(0, 0, 1)) {
pci_read_config_dword(bdf, PCI_CLASS_REVISION,
&class);
- if ((class >> 8 == PCI_CLASS_SERIAL_USB_EHCI)
- && !index--)
- return bdf;
+ class >>= 8;
+ /*
+ * Here be dragons! In case we have multiple
+ * PCI EHCI controllers, this function will
+ * be called multiple times as well. This
+ * function will scan the PCI busses, always
+ * starting from bus 0, device 0, function 0,
+ * until it finds an USB controller. The USB
+ * stack gives us an 'index' of a controller
+ * that is currently being registered, which
+ * is a number, starting from 0 and growing
+ * in ascending order as controllers are added.
+ * To avoid probing the same controller in tne
+ * subsequent runs of this function, we will
+ * skip 'index - 1' detected controllers and
+ * report the index'th controller.
+ */
+ if (class != PCI_CLASS_SERIAL_USB_EHCI)
+ continue;
+ if (index) {
+ index--;
+ continue;
+ }
+ /* Return index'th controller. */
+ return bdf;
}
}
}
--
1.8.4.3
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