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>

2 files changed, 23 insertions, 4 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) {
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index c3fdd6d69f5e..3421cf9858b5 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -605,8 +605,14 @@ musb_rx_reinit(struct musb *musb, struct musb_qh *qh, struct musb_hw_ep *ep)
         musb_writeb(ep->regs, MUSB_RXTYPE, qh->type_reg);
         musb_writeb(ep->regs, MUSB_RXINTERVAL, qh->intv_reg);
         /* NOTE: bulk combining rewrites high bits of maxpacket */
-        musb_writew(ep->regs, MUSB_RXMAXP,
-                        qh->maxpacket | ((qh->hb_mult - 1) << 11));
+        /* Set RXMAXP with the FIFO size of the endpoint
+         * to disable double buffer mode.
+         */
+        if (musb->hwvers < MUSB_HWVERS_2000)
+                musb_writew(ep->regs, MUSB_RXMAXP, ep->max_packet_sz_rx);
+        else
+                musb_writew(ep->regs, MUSB_RXMAXP,
+                                qh->maxpacket | ((qh->hb_mult - 1) << 11));
 
         ep->rx_reinit = 0;
 }