1 files changed, 43 insertions, 26 deletions

diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index 44b331a74d58..82434dde6e99 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -634,6 +634,7 @@ static void rxstate(struct musb *musb, struct musb_request *req)
 	u16			len;
 	u16			csr = musb_readw(epio, MUSB_RXCSR);
 	struct musb_hw_ep	*hw_ep = &musb->endpoints[epnum];
+	u8			use_mode_1;
 
 	if (hw_ep->is_shared_fifo)
 		musb_ep = &hw_ep->ep_in;
@@ -683,6 +684,18 @@ static void rxstate(struct musb *musb, struct musb_request *req)
 
 	if (csr & MUSB_RXCSR_RXPKTRDY) {
 		len = musb_readw(epio, MUSB_RXCOUNT);
+
+		/*
+		 * Enable Mode 1 on RX transfers only when short_not_ok flag
+		 * is set. Currently short_not_ok flag is set only from
+		 * file_storage and f_mass_storage drivers
+		 */
+
+		if (request->short_not_ok && len == musb_ep->packet_sz)
+			use_mode_1 = 1;
+		else
+			use_mode_1 = 0;
+
 		if (request->actual < request->length) {
 #ifdef CONFIG_USB_INVENTRA_DMA
 			if (is_buffer_mapped(req)) {
@@ -714,37 +727,41 @@ static void rxstate(struct musb *musb, struct musb_request *req)
 	 * then becomes usable as a runtime "use mode 1" hint...
 	 */
 
-				csr |= MUSB_RXCSR_DMAENAB;
-#ifdef USE_MODE1
-				csr |= MUSB_RXCSR_AUTOCLEAR;
-				/* csr |= MUSB_RXCSR_DMAMODE; */
-
-				/* this special sequence (enabling and then
-				 * disabling MUSB_RXCSR_DMAMODE) is required
-				 * to get DMAReq to activate
-				 */
-				musb_writew(epio, MUSB_RXCSR,
-					csr | MUSB_RXCSR_DMAMODE);
-#else
-				if (!musb_ep->hb_mult &&
-					musb_ep->hw_ep->rx_double_buffered)
+				/* Experimental: Mode1 works with mass storage use cases */
+				if (use_mode_1) {
 					csr |= MUSB_RXCSR_AUTOCLEAR;
-#endif
-				musb_writew(epio, MUSB_RXCSR, csr);
+					musb_writew(epio, MUSB_RXCSR, csr);
+					csr |= MUSB_RXCSR_DMAENAB;
+					musb_writew(epio, MUSB_RXCSR, csr);
+
+					/*
+					 * this special sequence (enabling and then
+					 * disabling MUSB_RXCSR_DMAMODE) is required
+					 * to get DMAReq to activate
+					 */
+					musb_writew(epio, MUSB_RXCSR,
+						csr | MUSB_RXCSR_DMAMODE);
+					musb_writew(epio, MUSB_RXCSR, csr);
+
+				} else {
+					if (!musb_ep->hb_mult &&
+						musb_ep->hw_ep->rx_double_buffered)
+						csr |= MUSB_RXCSR_AUTOCLEAR;
+					csr |= MUSB_RXCSR_DMAENAB;
+					musb_writew(epio, MUSB_RXCSR, csr);
+				}
 
 				if (request->actual < request->length) {
 					int transfer_size = 0;
-#ifdef USE_MODE1
-					transfer_size = min(request->length - request->actual,
-							channel->max_len);
-#else
-					transfer_size = min(request->length - request->actual,
-							(unsigned)len);
-#endif
-					if (transfer_size <= musb_ep->packet_sz)
-						musb_ep->dma->desired_mode = 0;
-					else
+					if (use_mode_1) {
+						transfer_size = min(request->length - request->actual,
+								channel->max_len);
 						musb_ep->dma->desired_mode = 1;
+					} else {
+						transfer_size = min(request->length - request->actual,
+								(unsigned)len);
+						musb_ep->dma->desired_mode = 0;
+					}
 
 					use_dma = c->channel_program(
 							channel,