EHCI: workaround for MosChip controller bug

[android-x86/kernel.git] / drivers / usb / host / ehci-sched.c

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 6c9fbe3..063c630 100644 (file)
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -36,6 +36,27 @@
 
 static int ehci_get_frame (struct usb_hcd *hcd);
 
+#ifdef CONFIG_PCI
+
+static unsigned ehci_read_frame_index(struct ehci_hcd *ehci)
+{
+       unsigned uf;
+
+       /*
+        * The MosChip MCS9990 controller updates its microframe counter
+        * a little before the frame counter, and occasionally we will read
+        * the invalid intermediate value.  Avoid problems by checking the
+        * microframe number (the low-order 3 bits); if they are 0 then
+        * re-read the register to get the correct value.
+        */
+       uf = ehci_readl(ehci, &ehci->regs->frame_index);
+       if (unlikely(ehci->frame_index_bug && ((uf & 7) == 0)))
+               uf = ehci_readl(ehci, &ehci->regs->frame_index);
+       return uf;
+}
+
+#endif
+
 /*-------------------------------------------------------------------------*/
 
 /*
@@ -482,7 +503,7 @@ static int enable_periodic (struct ehci_hcd *ehci)
        ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
 
        /* make sure ehci_work scans these */
-       ehci->next_uframe = ehci_readl(ehci, &ehci->regs->frame_index)
+       ehci->next_uframe = ehci_read_frame_index(ehci)
                % (ehci->periodic_size << 3);
        if (unlikely(ehci->broken_periodic))
                ehci->last_periodic_enable = ktime_get_real();
@@ -1412,7 +1433,7 @@ iso_stream_schedule (
                goto fail;
        }
 
-       now = ehci_readl(ehci, &ehci->regs->frame_index) & (mod - 1);
+       now = ehci_read_frame_index(ehci) & (mod - 1);
 
        /* Typical case: reuse current schedule, stream is still active.
         * Hopefully there are no gaps from the host falling behind
@@ -2279,7 +2300,7 @@ scan_periodic (struct ehci_hcd *ehci)
         */
        now_uframe = ehci->next_uframe;
        if (HC_IS_RUNNING(ehci_to_hcd(ehci)->state)) {
-               clock = ehci_readl(ehci, &ehci->regs->frame_index);
+               clock = ehci_read_frame_index(ehci);
                clock_frame = (clock >> 3) & (ehci->periodic_size - 1);
        } else  {
                clock = now_uframe + mod - 1;
@@ -2458,8 +2479,7 @@ restart:
                                        || ehci->periodic_sched == 0)
                                break;
                        ehci->next_uframe = now_uframe;
-                       now = ehci_readl(ehci, &ehci->regs->frame_index) &
-                                       (mod - 1);
+                       now = ehci_read_frame_index(ehci) & (mod - 1);
                        if (now_uframe == now)
                                break;