[PATCH] Cochran: Add read retry

[John Van Ostrand]

Using FTDI for custom_io resulted in very unrealible reads. This
patch allows more reliable use of FTDI custom io, like what might
be needed when used on a mobile device like Android.
---
 src/cochran_commander.c | 34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/cochran_commander.c b/src/cochran_commander.c
index 921c8c0..1de6c07 100644
--- a/src/cochran_commander.c
+++ b/src/cochran_commander.c
@@ -806,11 +806,39 @@ cochran_commander_device_set_fingerprint (dc_device_t *abstract, const unsigned
 
 
 static dc_status_t
+cochran_commander_read_retry(cochran_commander_device_t *device, dc_event_progress_t *progress, unsigned int address, unsigned char data[], unsigned int size)
+{
+
+	dc_status_t rc = DC_STATUS_SUCCESS;
+	unsigned int nretries = 0;
+	int last_current = 0;
+
+	if (progress)
+		last_current = progress->current;
+
+	while (nretries < 3) {
+		if (nretries)
+			WARNING(device->base.context, "Read error, attempting retry.");
+
+		rc = cochran_commander_read(device, progress, address, data, size);
+		if (rc == DC_STATUS_SUCCESS)
+			return rc;
+
+		nretries++;
+		if (progress)
+			progress->current = last_current;
+	}
+
+	return rc;
+}
+
+
+static dc_status_t
 cochran_commander_device_read (dc_device_t *abstract, unsigned int address, unsigned char data[], unsigned int size)
 {
 	cochran_commander_device_t *device = (cochran_commander_device_t *) abstract;
 
-	return cochran_commander_read(device, NULL, address, data, size);
+	return cochran_commander_read_retry(device, NULL, address, data, size);
 }
 
 
@@ -854,7 +882,7 @@ cochran_commander_device_dump (dc_device_t *abstract, dc_buffer_t *buffer)
 		return rc;
 
 	// Read the sample data, logbook and sample data are contiguous
-	rc = cochran_commander_read (device, &progress, device->layout->rb_logbook_begin, dc_buffer_get_data(buffer), size);
+	rc = cochran_commander_read_retry (device, &progress, device->layout->rb_logbook_begin, dc_buffer_get_data(buffer), size);
 	if (rc != DC_STATUS_SUCCESS) {
 		ERROR (abstract->context, "Failed to read the sample data.");
 		return rc;
@@ -934,7 +962,7 @@ cochran_commander_device_foreach (dc_device_t *abstract, dc_dive_callback_t call
 	}
 
 	// Request log book
-	rc = cochran_commander_read(device, &progress, layout->rb_logbook_begin, data.logbook, data.logbook_size);
+	rc = cochran_commander_read_retry(device, &progress, layout->rb_logbook_begin, data.logbook, data.logbook_size);
 	if (rc != DC_STATUS_SUCCESS) {
 		status = rc;
 		goto error;
-- 
2.4.11