NFC: pn533: Don't use out_frame in pn533_send_ack

dev->out_frame buffer is much bigger for ACK frame needs. Use
local buffer instead.

Signed-off-by: Waldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

diff --git a/drivers/nfc/pn533.c b/drivers/nfc/pn533.c
index 5fb5b8f..5bc0c7c 100644 (file)
--- a/drivers/nfc/pn533.c
+++ b/drivers/nfc/pn533.c
@@ -94,7 +94,8 @@ MODULE_DEVICE_TABLE(usb, pn533_table);
 
 #define PN533_FRAME_SIZE(f) (sizeof(struct pn533_frame) + f->datalen + \
                                PN533_FRAME_TAIL_LEN)
-#define PN533_FRAME_ACK_SIZE (sizeof(struct pn533_frame) + 1)
+#define PN533_FRAME_ACK_SIZE 6 /* Preamble (1), SoPC (2), ACK Code (2),
+                                 Postamble (1) */
 #define PN533_FRAME_CHECKSUM(f) (f->data[f->datalen])
 #define PN533_FRAME_POSTAMBLE(f) (f->data[f->datalen + 1])
 
@@ -402,26 +403,6 @@ static u8 pn533_data_checksum(u8 *data, int datalen)
        return pn533_checksum(sum);
 }
 
-/**
- * pn533_tx_frame_ack - create a ack frame
- * @frame:     The frame to be set as ack
- *
- * Ack is different type of standard frame. As a standard frame, it has
- * preamble and start_frame. However the checksum of this frame must fail,
- * i.e. datalen + datalen_checksum must NOT be zero. When the checksum test
- * fails and datalen = 0 and datalen_checksum = 0xFF, the frame is a ack.
- * After datalen_checksum field, the postamble is placed.
- */
-static void pn533_tx_frame_ack(struct pn533_frame *frame)
-{
-       frame->preamble = 0;
-       frame->start_frame = cpu_to_be16(PN533_SOF);
-       frame->datalen = 0;
-       frame->datalen_checksum = 0xFF;
-       /* data[0] is used as postamble */
-       frame->data[0] = 0;
-}
-
 static void pn533_tx_frame_init(struct pn533_frame *frame, u8 cmd)
 {
        frame->preamble = 0;
@@ -612,14 +593,14 @@ static int pn533_submit_urb_for_ack(struct pn533 *dev, gfp_t flags)
 
 static int pn533_send_ack(struct pn533 *dev, gfp_t flags)
 {
+       u8 ack[PN533_FRAME_ACK_SIZE] = {0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
+       /* spec 7.1.1.3:  Preamble, SoPC (2), ACK Code (2), Postamble */
        int rc;
 
        nfc_dev_dbg(&dev->interface->dev, "%s", __func__);
 
-       pn533_tx_frame_ack(dev->out_frame);
-
-       dev->out_urb->transfer_buffer = dev->out_frame;
-       dev->out_urb->transfer_buffer_length = PN533_FRAME_ACK_SIZE;
+       dev->out_urb->transfer_buffer = ack;
+       dev->out_urb->transfer_buffer_length = sizeof(ack);
        rc = usb_submit_urb(dev->out_urb, flags);
 
        return rc;