USB: ehci refcounts work on ppc7448

Remove atomic operations on the reference counter for EHCI queue heads.
On various platforms (including ppc7448), atomic operations are unusable
with dma-coherent memory.

Signed-off-by: Steven J. Hill <sjhill1@rockwellcollins.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 79ad2af5ef6a..6ef9d775775b 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -457,7 +457,14 @@ struct ehci_qh {
         struct ehci_qh          *reclaim;       /* next to reclaim */
 
         struct ehci_hcd         *ehci;
-        struct kref             kref;
+
+        /*
+         * Do NOT use atomic operations for QH refcounting. On some CPUs
+         * (PPC7448 for example), atomic operations cannot be performed on
+         * memory that is cache-inhibited (i.e. being used for DMA).
+         * Spinlocks are used to protect all QH fields.
+         */
+        u32                     refcount;
         unsigned                stamp;
 
         u8                      qh_state;