sysclk-lwla: Drain pending replies on initialization

When opening the device, drain any pending data from the USB
buffers so that the device won't get stuck on crashes etc.

diff --git a/src/hardware/sysclk-lwla/api.c b/src/hardware/sysclk-lwla/api.c
index 7dfd7582f67c539219f199c2f2bebf9733977e34..e8c2cb0cdf359fc98f5d9ad2246d3f6d3361c9b7 100644 (file)
--- a/src/hardware/sysclk-lwla/api.c
+++ b/src/hardware/sysclk-lwla/api.c
@@ -248,6 +248,40 @@ static int dev_clear(const struct sr_dev_driver *di)
        return std_dev_clear(di, &clear_dev_context);
 }
 
+/* Drain any pending data from the USB transfer buffers on the device.
+ * This may be necessary e.g. after a crash or generally to clean up after
+ * an abnormal condition.
+ */
+static int drain_usb(struct sr_usb_dev_inst *usb, unsigned int endpoint)
+{
+       int drained, xfer_len;
+       int ret;
+       unsigned char buf[512];
+
+       const unsigned int drain_timeout_ms = 10;
+
+       drained = 0;
+       do {
+               xfer_len = 0;
+               ret = libusb_bulk_transfer(usb->devhdl, endpoint,
+                                          buf, sizeof buf, &xfer_len,
+                                          drain_timeout_ms);
+               drained += xfer_len;
+       } while (ret == LIBUSB_SUCCESS && xfer_len != 0);
+
+       if (ret != LIBUSB_SUCCESS && ret != LIBUSB_ERROR_TIMEOUT) {
+               sr_err("Failed to drain USB endpoint %u: %s.",
+                      endpoint & (LIBUSB_ENDPOINT_IN - 1),
+                      libusb_error_name(ret));
+               return SR_ERR;
+       }
+       if (drained > 0) {
+               sr_warn("Drained %d bytes from USB endpoint %u.",
+                       drained, endpoint & (LIBUSB_ENDPOINT_IN - 1));
+       }
+       return SR_OK;
+}
+
 /* Open and initialize device.
  */
 static int dev_open(struct sr_dev_inst *sdi)
@@ -275,7 +309,7 @@ static int dev_open(struct sr_dev_inst *sdi)
                return ret;
 
        ret = libusb_set_configuration(usb->devhdl, USB_CONFIG);
-       if (ret != 0) {
+       if (ret != LIBUSB_SUCCESS) {
                sr_err("Failed to set USB configuration: %s.",
                        libusb_error_name(ret));
                sr_usb_close(usb);
@@ -283,13 +317,17 @@ static int dev_open(struct sr_dev_inst *sdi)
        }
 
        ret = libusb_claim_interface(usb->devhdl, USB_INTERFACE);
-       if (ret < 0) {
+       if (ret != LIBUSB_SUCCESS) {
                sr_err("Failed to claim interface: %s.",
                        libusb_error_name(ret));
                sr_usb_close(usb);
                return SR_ERR;
        }
 
+       ret = drain_usb(usb, EP_REPLY);
+       if (ret != SR_OK)
+               return ret;
+
        sdi->status = SR_ST_ACTIVE;
 
        devc->active_fpga_config = FPGA_NOCONF;

diff --git a/src/hardware/sysclk-lwla/lwla.h b/src/hardware/sysclk-lwla/lwla.h
index f0f280fa10422a42cdc0b2e4e230ea154b1166ba..35e3b0ea59044ffbf10e6005f32bc98765f7db5e 100644 (file)
--- a/src/hardware/sysclk-lwla/lwla.h
+++ b/src/hardware/sysclk-lwla/lwla.h
@@ -69,14 +69,6 @@ struct sr_usb_dev_inst;
  */
 #define PACKET_SIZE            (5000 * 4 * 5)
 
-/** USB device end points.
- */
-enum usb_endpoint {
-       EP_COMMAND = 2,
-       EP_CONFIG  = 4,
-       EP_REPLY   = 6 | LIBUSB_ENDPOINT_IN
-};
-
 /** LWLA protocol command ID codes.
  */
 enum command_id {

diff --git a/src/hardware/sysclk-lwla/protocol.h b/src/hardware/sysclk-lwla/protocol.h
index 355b5c0a1a9d66f1a0d79a05ae0fa73a15afe35e..9ef21b05de0b26d6505af25b085e441cafb28921 100644 (file)
--- a/src/hardware/sysclk-lwla/protocol.h
+++ b/src/hardware/sysclk-lwla/protocol.h
@@ -23,6 +23,7 @@
 #define LOG_PREFIX "sysclk-lwla"
 
 #include <stdint.h>
+#include <libusb.h>
 #include <glib.h>
 #include <libsigrok/libsigrok.h>
 #include <libsigrok-internal.h>
@@ -61,6 +62,14 @@ enum {
        USB_TIMEOUT_MS  = 3000,
 };
 
+/** USB device end points.
+ */
+enum usb_endpoint {
+       EP_COMMAND = 2,
+       EP_CONFIG  = 4,
+       EP_REPLY   = 6 | LIBUSB_ENDPOINT_IN
+};
+
 /** LWLA1034 clock sources.
  */
 enum clock_source {