USB: musb: disable double buffering for older RTL versions

Trying to use double buffer modes in RTL versions <2.0 may result in
infinite hangs or data corruption.  So avoid them with older versions.

Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index cbcf14a236e6..41de3a903152 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -895,7 +895,14 @@ static int musb_gadget_enable(struct usb_ep *ep,
                 /* REVISIT if can_bulk_split(), use by updating "tmp";
                  * likewise high bandwidth periodic tx
                  */
-                musb_writew(regs, MUSB_TXMAXP, tmp);
+                /* Set TXMAXP with the FIFO size of the endpoint
+                 * to disable double buffering mode. Currently, It seems that double
+                 * buffering has problem if musb RTL revision number < 2.0.
+                 */
+                if (musb->hwvers < MUSB_HWVERS_2000)
+                        musb_writew(regs, MUSB_TXMAXP, hw_ep->max_packet_sz_tx);
+                else
+                        musb_writew(regs, MUSB_TXMAXP, tmp);
 
                 csr = MUSB_TXCSR_MODE | MUSB_TXCSR_CLRDATATOG;
                 if (musb_readw(regs, MUSB_TXCSR)
@@ -925,7 +932,13 @@ static int musb_gadget_enable(struct usb_ep *ep,
                 /* REVISIT if can_bulk_combine() use by updating "tmp"
                  * likewise high bandwidth periodic rx
                  */
-                musb_writew(regs, MUSB_RXMAXP, tmp);
+                /* Set RXMAXP with the FIFO size of the endpoint
+                 * to disable double buffering mode.
+                 */
+                if (musb->hwvers < MUSB_HWVERS_2000)
+                        musb_writew(regs, MUSB_RXMAXP, hw_ep->max_packet_sz_rx);
+                else
+                        musb_writew(regs, MUSB_RXMAXP, tmp);
 
                 /* force shared fifo to OUT-only mode */
                 if (hw_ep->is_shared_fifo) {