usb: musb: Add quirk to avoid skb reserve in gadget mode

For tusb6010 the DMA functionality only possible if the buffer is 32bit
aligned (SYNC access to FIFO) since with ASYNC access the TX/RX offset
registers will corrupt eventually.
The MUSB_G_NO_SKB_RESERVE will set the quirk_avoids_skb_reserve flag in
usb_gadget struct to provide correctly aligned buffer.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_core.c

@@ -2224,6 +2224,9 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
 		musb->io.ep_select = musb_flat_ep_select;
 	}
 
+	if (musb->io.quirks & MUSB_G_NO_SKB_RESERVE)
+		musb->g.quirk_avoids_skb_reserve = 1;
+
 	/* At least tusb6010 has its own offsets */
 	if (musb->ops->ep_offset)
 		musb->io.ep_offset = musb->ops->ep_offset;

drivers/usb/musb/musb_core.h

@@ -172,6 +172,7 @@ struct musb_io;
  */
 struct musb_platform_ops {
 
+#define MUSB_G_NO_SKB_RESERVE	BIT(9)
 #define MUSB_DA8XX		BIT(8)
 #define MUSB_PRESERVE_SESSION	BIT(7)
 #define MUSB_DMA_UX500		BIT(6)