usb: chipidea: udc: Support SKB alignment quirk

NVIDIA Tegra20 UDC can't cope with unaligned DMA and require a USB gadget
quirk that avoids SKB buffer alignment to be set in order to make Ethernet
Gadget working. Later Tegra generations do not require that quirk. Let's
add a new platform data flag that allows to enable USB gadget quirk for
platforms that require it.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>

drivers/usb/chipidea/udc.c

@@ -1896,6 +1896,9 @@ static int udc_start(struct ci_hdrc *ci)
 	ci->gadget.name         = ci->platdata->name;
 	ci->gadget.otg_caps	= otg_caps;
 
+	if (ci->platdata->flags & CI_HDRC_REQUIRES_ALIGNED_DMA)
+		ci->gadget.quirk_avoids_skb_reserve = 1;
+
 	if (ci->is_otg && (otg_caps->hnp_support || otg_caps->srp_support ||
 						otg_caps->adp_support))
 		ci->gadget.is_otg = 1;

include/linux/usb/chipidea.h

@@ -58,6 +58,7 @@ struct ci_hdrc_platform_data {
 #define CI_HDRC_OVERRIDE_TX_BURST	BIT(10)
 #define CI_HDRC_OVERRIDE_RX_BURST	BIT(11)
 #define CI_HDRC_OVERRIDE_PHY_CONTROL	BIT(12) /* Glue layer manages phy */
+#define CI_HDRC_REQUIRES_ALIGNED_DMA	BIT(13)
 	enum usb_dr_mode	dr_mode;
 #define CI_HDRC_CONTROLLER_RESET_EVENT		0
 #define CI_HDRC_CONTROLLER_STOPPED_EVENT	1