usb: dwc2: gadget: don't embed ep0 buffers

When using DMA, data of the previous setup packet can be read back
from cache because ep0 and ctrl buffers are embedded in struct s3c_hsotg.
Allocate buffers instead of embedding them.
Tested-by: NRobert Baldyga <r.baldyga@samsung.com>
Acked-by: NPaul Zimmerman <paulz@synopsys.com>
Signed-off-by: NMian Yousaf Kaukab <yousaf.kaukab@intel.com>
Reviewed-by: NRobert Baldyga <r.baldyga@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/dwc2/core.h

@@ -434,6 +434,9 @@ struct dwc2_hw_params {
 	u32 snpsid;
 };
 
+/* Size of control and EP0 buffers */
+#define DWC2_CTRL_BUFF_SIZE 8
+
 /**
  * struct dwc2_hsotg - Holds the state of the driver, including the non-periodic
  * and periodic schedules
@@ -684,8 +687,8 @@ struct dwc2_hsotg {
 
 	struct usb_request *ep0_reply;
 	struct usb_request *ctrl_req;
-	u8 ep0_buff[8];
-	u8 ctrl_buff[8];
+	void *ep0_buff;
+	void *ctrl_buff;
 
 	struct usb_gadget gadget;
 	unsigned int enabled:1;

drivers/usb/dwc2/gadget.c

@@ -3486,6 +3486,22 @@ int dwc2_gadget_init(struct dwc2_hsotg *hsotg, int irq)
 	s3c_hsotg_hw_cfg(hsotg);
 	s3c_hsotg_init(hsotg);
 
+	hsotg->ctrl_buff = devm_kzalloc(hsotg->dev,
+			DWC2_CTRL_BUFF_SIZE, GFP_KERNEL);
+	if (!hsotg->ctrl_buff) {
+		dev_err(dev, "failed to allocate ctrl request buff\n");
+		ret = -ENOMEM;
+		goto err_supplies;
+	}
+
+	hsotg->ep0_buff = devm_kzalloc(hsotg->dev,
+			DWC2_CTRL_BUFF_SIZE, GFP_KERNEL);
+	if (!hsotg->ep0_buff) {
+		dev_err(dev, "failed to allocate ctrl reply buff\n");
+		ret = -ENOMEM;
+		goto err_supplies;
+	}
+
 	ret = devm_request_irq(hsotg->dev, irq, s3c_hsotg_irq, IRQF_SHARED,
 				dev_name(hsotg->dev), hsotg);
 	if (ret < 0) {