usb: musb: tusb6010_omap: Do not reset the other direction's packet size

We have one register for each EP to set the maximum packet size for both
TX and RX.
If for example an RX programming would happen before the previous TX
transfer finishes we would reset the TX packet side.

To fix this issue, only modify the TX or RX part of the register.

Fixes: 550a737 ("USB: Add MUSB and TUSB support")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/tusb6010_omap.c

@@ -219,6 +219,7 @@ static int tusb_omap_dma_program(struct dma_channel *channel, u16 packet_sz,
 	u32				dma_remaining;
 	int				src_burst, dst_burst;
 	u16				csr;
+	u32				psize;
 	int				ch;
 	s8				dmareq;
 	s8				sync_dev;
@@ -390,15 +391,19 @@ static int tusb_omap_dma_program(struct dma_channel *channel, u16 packet_sz,
 
 	if (chdat->tx) {
 		/* Send transfer_packet_sz packets at a time */
-		musb_writel(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET,
-			chdat->transfer_packet_sz);
+		psize = musb_readl(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET);
+		psize &= ~0x7ff;
+		psize |= chdat->transfer_packet_sz;
+		musb_writel(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET, psize);
 
 		musb_writel(ep_conf, TUSB_EP_TX_OFFSET,
 			TUSB_EP_CONFIG_XFR_SIZE(chdat->transfer_len));
 	} else {
 		/* Receive transfer_packet_sz packets at a time */
-		musb_writel(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET,
-			chdat->transfer_packet_sz << 16);
+		psize = musb_readl(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET);
+		psize &= ~(0x7ff << 16);
+		psize |= (chdat->transfer_packet_sz << 16);
+		musb_writel(ep_conf, TUSB_EP_MAX_PACKET_SIZE_OFFSET, psize);
 
 		musb_writel(ep_conf, TUSB_EP_RX_OFFSET,
 			TUSB_EP_CONFIG_XFR_SIZE(chdat->transfer_len));