usb: ohci: Default to per-port over-current protection

Some integrated OHCI controller hubs do not expose all ports of the hub
to pins on the SoC. In some cases the unconnected ports generate
spurious over-current events. For example the Broadcom 56060/Ranger 2 SoC
contains a nominally 3 port hub but only the first port is wired.

Default behaviour for ohci-platform driver is to use global over-current
protection mode (AKA "ganged"). This leads to the spurious over-current
events affecting all ports in the hub.

We now alter the default to use per-port over-current protection.

This patch results in the following configuration changes depending
on quirks:
- For quirk OHCI_QUIRK_SUPERIO no changes. These systems remain set up
  for ganged power switching and no over-current protection.
- For quirk OHCI_QUIRK_AMD756 or OHCI_QUIRK_HUB_POWER power switching
  remains at none, while over-current protection is now guaranteed to be
  set to per-port rather than the previous behaviour where it was either
  none or global over-current protection depending on the value at
  function entry.

Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20200910212512.16670-1-hamish.martin@alliedtelesis.co.nz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index dd37e77dae0014731a692d58e5070f98c1ffbe07..2845ea328a064392dd789724eaa4159a4a778895 100644 (file)
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -673,20 +673,24 @@ retry:
 
        /* handle root hub init quirks ... */
        val = roothub_a (ohci);
-       val &= ~(RH_A_PSM | RH_A_OCPM);
+       /* Configure for per-port over-current protection by default */
+       val &= ~RH_A_NOCP;
+       val |= RH_A_OCPM;
        if (ohci->flags & OHCI_QUIRK_SUPERIO) {
-               /* NSC 87560 and maybe others */
+               /* NSC 87560 and maybe others.
+                * Ganged power switching, no over-current protection.
+                */
                val |= RH_A_NOCP;
-               val &= ~(RH_A_POTPGT | RH_A_NPS);
-               ohci_writel (ohci, val, &ohci->regs->roothub.a);
+               val &= ~(RH_A_POTPGT | RH_A_NPS | RH_A_PSM | RH_A_OCPM);
        } else if ((ohci->flags & OHCI_QUIRK_AMD756) ||
                        (ohci->flags & OHCI_QUIRK_HUB_POWER)) {
                /* hub power always on; required for AMD-756 and some
-                * Mac platforms.  ganged overcurrent reporting, if any.
+                * Mac platforms.
                 */
                val |= RH_A_NPS;
-               ohci_writel (ohci, val, &ohci->regs->roothub.a);
        }
+       ohci_writel(ohci, val, &ohci->regs->roothub.a);
+
        ohci_writel (ohci, RH_HS_LPSC, &ohci->regs->roothub.status);
        ohci_writel (ohci, (val & RH_A_NPS) ? 0 : RH_B_PPCM,
                                                &ohci->regs->roothub.b);