speed up ftdi by reorder to out-in

[openocd.git] / src / jtag / drivers / mpsse.c

diff --git a/src/jtag/drivers/mpsse.c b/src/jtag/drivers/mpsse.c
index d6cbc8404c6e93330f3f38d6ed87317776b0e617..41429693c15fe8a347de26cbf3e2d3a9b526e4b8 100644 (file)
--- a/src/jtag/drivers/mpsse.c
+++ b/src/jtag/drivers/mpsse.c
@@ -779,11 +779,8 @@ int mpsse_flush(struct mpsse_ctx *ctx)
        if (ctx->read_count) {
                buffer_write_byte(ctx, 0x87); /* SEND_IMMEDIATE */
                read_result.done = false;
-               read_transfer = libusb_alloc_transfer(0);
-               libusb_fill_bulk_transfer(read_transfer, ctx->usb_dev, ctx->in_ep, ctx->read_chunk,
-                       ctx->read_chunk_size, read_cb, &read_result,
-                       ctx->usb_read_timeout);
-               retval = libusb_submit_transfer(read_transfer);
+               /* delay read transaction to ensure the FTDI chip can support us with data
+                  immediately after processing the MPSSE commands in the write transaction */
        }
 
        struct transfer_result write_result = { .ctx = ctx, .done = false };
@@ -792,6 +789,14 @@ int mpsse_flush(struct mpsse_ctx *ctx)
                ctx->write_count, write_cb, &write_result, ctx->usb_write_timeout);
        retval = libusb_submit_transfer(write_transfer);
 
+       if (ctx->read_count) {
+               read_transfer = libusb_alloc_transfer(0);
+               libusb_fill_bulk_transfer(read_transfer, ctx->usb_dev, ctx->in_ep, ctx->read_chunk,
+                       ctx->read_chunk_size, read_cb, &read_result,
+                       ctx->usb_read_timeout);
+               retval = libusb_submit_transfer(read_transfer);
+       }
+
        /* Polling loop, more or less taken from libftdi */
        while (!write_result.done || !read_result.done) {
                retval = libusb_handle_events(ctx->usb_ctx);