[PATCH 3.19 087/177] xhci: Allocate correct amount of scratchpad buffers

Greg Kroah-Hartman
2015-03-16T14:14:51Z

From: Mathias Nyman <mathias.nyman@linux.intel.com>

commit 6596a926b0b6c80b730a1dd2fa91908e0a539c37 upstream.

Include the high order bit fields for Max scratchpad buffers when
calculating how many scratchpad buffers are needed.

I'm suprised this hasn't caused more issues, we never allocated more than
32 buffers even if xhci needed more. Either we got lucky and xhci never
really used past that area, or then we got enough zeroed dma memory anyway.

Should be backported as far back as possible

Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Tested-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/host/xhci.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -88,9 +88,10 @@ struct xhci_cap_regs {
#define HCS_IST(p) (((p) >> 0) & 0xf)
/* bits 4:7, max number of Event Ring segments */
#define HCS_ERST_MAX(p) (((p) >> 4) & 0xf)
+/* bits 21:25 Hi 5 bits of Scratchpad buffers SW must allocate for the HW */
/* bit 26 Scratchpad restore - for save/restore HW state - not used yet */
-/* bits 27:31 number of Scratchpad buffers SW must allocate for the HW */
-#define HCS_MAX_SCRATCHPAD(p) (((p) >> 27) & 0x1f)
+/* bits 27:31 Lo 5 bits of Scratchpad buffers SW must allocate for the HW */
+#define HCS_MAX_SCRATCHPAD(p) ((((p) >> 16) & 0x3e0) | (((p) >> 27) & 0x1f))

/* HCSPARAMS3 - hcs_params3 - bitmasks */
/* bits 0:7, Max U1 to U0 latency for the roothub ports */