sysclk-lwla: Utility functions clean-up and semantic fixes.

(lwla_send_bitstream): Unref the mapped file earlier in order
to simplify the error handling.
(lwla_receive_reply): Do not treat a reply buffer length of
zero as silent no-op.  That logic was left over from an earlier
iteration, before the distinction between reply buffer size and
expected read length was introduced.

diff --git a/hardware/sysclk-lwla/lwla.c b/hardware/sysclk-lwla/lwla.c
index 82dc90d4d75f093b4550e71bfaa6074b744bd516..ad0bf5a17b9b349986781094aaa73b09be59599e 100644 (file)
--- a/hardware/sysclk-lwla/lwla.c
+++ b/hardware/sysclk-lwla/lwla.c
@@ -58,19 +58,18 @@ SR_PRIV int lwla_send_bitstream(const struct sr_usb_dev_inst *usb,
        ret = libusb_bulk_transfer(usb->devhdl, EP_BITSTREAM,
                                   (unsigned char *)stream, length,
                                   &xfer_len, USB_TIMEOUT);
+       g_mapped_file_unref(file);
+
        if (ret != 0) {
                sr_err("Failed to transfer bitstream: %s.",
                       libusb_error_name(ret));
-               g_mapped_file_unref(file);
                return SR_ERR;
        }
        if (xfer_len != (int)length) {
                sr_err("Failed to transfer bitstream: incorrect length "
                       "%d != %d.", xfer_len, (int)length);
-               g_mapped_file_unref(file);
                return SR_ERR;
        }
-       g_mapped_file_unref(file);
        sr_info("FPGA bitstream download of %d bytes done.", xfer_len);
 
        /* This delay appears to be necessary for reliable operation. */
@@ -83,11 +82,12 @@ SR_PRIV int lwla_send_command(const struct sr_usb_dev_inst *usb,
                              const uint16_t *command, int cmd_len)
 {
        int ret;
-       int xfer_len = 0;
+       int xfer_len;
 
-       if (usb == NULL || command == NULL || cmd_len < 1)
+       if (usb == NULL || command == NULL || cmd_len <= 0)
                return SR_ERR_ARG;
 
+       xfer_len = 0;
        ret = libusb_bulk_transfer(usb->devhdl, EP_COMMAND,
                                   (unsigned char *)command, cmd_len * 2,
                                   &xfer_len, USB_TIMEOUT);
@@ -108,14 +108,12 @@ SR_PRIV int lwla_receive_reply(const struct sr_usb_dev_inst *usb,
                               uint16_t *reply, int reply_len, int expect_len)
 {
        int ret;
-       int xfer_len = 0;
-
-       if (reply_len == 0)
-               return SR_OK;
+       int xfer_len;
 
-       if (usb == NULL || reply == NULL || reply_len < 0)
+       if (usb == NULL || reply == NULL || reply_len <= 0)
                return SR_ERR_ARG;
 
+       xfer_len = 0;
        ret = libusb_bulk_transfer(usb->devhdl, EP_REPLY,
                                   (unsigned char *)reply, reply_len * 2,
                                   &xfer_len, USB_TIMEOUT);
@@ -136,7 +134,7 @@ SR_PRIV int lwla_read_reg(const struct sr_usb_dev_inst *usb,
 {
        int ret;
        uint16_t command[2];
-       uint16_t reply[256];
+       uint16_t reply[256]; /* full EP buffer to avoid overflows */
 
        command[0] = LWLA_WORD(CMD_READ_REG);
        command[1] = LWLA_WORD(reg);