firehose: Improve startup time significantly

The firehose_read() at the start of firehose_run() serves the purpose of
waiting for the programmer to show up and to consume any <log/> messages
spat out, so that we're ready to invoke the <configure/>.

On MSM8916 there are no <log/> entries, so this is a 5 second loop
hitting -ETIMEDOUTs in firehose_read(). On other tested targets, it does
drain the <log/> entries and then hits -ETIMEDOUTs for the remainder of
5 seconds.

On the newer targets, we could perhaps determine when the programmer is
up by looking for <log/> entries, but this doesn't help the MSM8916
model and it doesn't fit with the current implementation.

If we instead tweak the timeouts and error handling of
firehose_configure(), we can speculatively attempt to configure the
programmer until success.

This meets both the observed models, and shows savings between 4 and 4.5
seconds in startup time across the tested devices.

Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>

firehose.c

@@ -305,7 +305,6 @@ static int firehose_send_configure(struct qdl_device *qdl, size_t payload_size,
 	xmlNode *root;
 	xmlNode *node;
 	xmlDoc *doc;
-	int ret;
 
 	doc = xmlNewDoc((xmlChar *)"1.0");
 	root = xmlNewNode(NULL, (xmlChar *)"data");
@@ -318,16 +317,14 @@ static int firehose_send_configure(struct qdl_device *qdl, size_t payload_size,
 	xml_setpropf(node, "ZLPAwareHost", "%d", 1);
 	xml_setpropf(node, "SkipStorageInit", "%d", skip_storage_init);
 
-	ret = firehose_write(qdl, doc);
+	firehose_write(qdl, doc);
 	xmlFreeDoc(doc);
-	if (ret < 0)
-		return ret;
 
-	return firehose_read(qdl, 5000, firehose_configure_response_parser, max_payload_size);
+	return firehose_read(qdl, 100, firehose_configure_response_parser, max_payload_size);
 }
 
-static int firehose_configure(struct qdl_device *qdl, bool skip_storage_init,
-			      const char *storage)
+static int firehose_try_configure(struct qdl_device *qdl, bool skip_storage_init,
+				  const char *storage)
 {
 	size_t max_sector_size;
 	size_t sector_sizes[] = { 512, 4096 };
@@ -339,10 +336,8 @@ static int firehose_configure(struct qdl_device *qdl, bool skip_storage_init,
 
 	ret = firehose_send_configure(qdl, qdl->max_payload_size, skip_storage_init,
 				      storage, &size);
-	if (ret < 0) {
-		ux_err("configure request failed\n");
-		return -1;
-	}
+	if (ret < 0)
+		return ret;
 
 	/*
 	 * In simulateion mode "remote" target can't propose different size, so
@@ -932,13 +927,42 @@ static int firehose_reset(struct qdl_device *qdl)
 	return ret == FIREHOSE_ACK ? 0 : -1;
 }
 
+static int firehose_detect_and_configure(struct qdl_device *qdl,
+					 bool skip_storage_init,
+					 const char *storage,
+					 unsigned int timeout_s)
+{
+	struct timeval timeout = { .tv_sec = timeout_s };
+	struct timeval now;
+	int ret;
+
+	gettimeofday(&now, NULL);
+	timeradd(&now, &timeout, &timeout);
+	for (;;) {
+		ret = firehose_try_configure(qdl, false, storage);
+
+		if (ret == FIREHOSE_ACK) {
+			break;
+		} else if (ret != -ETIMEDOUT) {
+			ux_err("configure request failed\n");
+			return -1;
+		}
+
+		gettimeofday(&now, NULL);
+		if (timercmp(&now, &timeout, >)) {
+			ux_err("failed to detect firehose programmer\n");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 int firehose_provision(struct qdl_device *qdl)
 {
 	int ret;
 
-	firehose_read(qdl, 5000, firehose_generic_parser, NULL);
-
-	ret = firehose_configure(qdl, true, "ufs");
+	ret = firehose_detect_and_configure(qdl, true, "ufs", 5);
 	if (ret)
 		return ret;
 
@@ -964,9 +988,7 @@ int firehose_run(struct qdl_device *qdl, const char *storage)
 
 	ux_info("waiting for programmer...\n");
 
-	firehose_read(qdl, 5000, firehose_generic_parser, NULL);
-
-	ret = firehose_configure(qdl, false, storage);
+	ret = firehose_detect_and_configure(qdl, true, storage, 5);
 	if (ret)
 		return ret;
 

io.c

@@ -53,6 +53,15 @@ int qdl_read(struct qdl_device *qdl, void *buf, size_t len, unsigned int timeout
 	return qdl->read(qdl, buf, len, timeout);
 }
 
+/**
+ * qdl_write() - Write a message from the device
+ * @qdl: device handle
+ * @buf: buffer with data to be written
+ * @len: length of data to be written
+ *
+ * Returns: number of bytes read
+ *	    negative errno on failure (notably -ETIMEDOUT)
+ */
 int qdl_write(struct qdl_device *qdl, const void *buf, size_t len)
 {
 	return qdl->write(qdl, buf, len);

usb.c

@@ -262,11 +262,12 @@ static int usb_write(struct qdl_device *qdl, const void *buf, size_t len)
 
 		ret = libusb_bulk_transfer(qdl_usb->usb_handle, qdl_usb->out_ep, data,
 					   xfer, &actual, 1000);
-		if ((ret != 0 && ret != LIBUSB_ERROR_TIMEOUT) ||
-		    (ret == LIBUSB_ERROR_TIMEOUT && actual == 0)) {
+		if (ret != 0 && ret != LIBUSB_ERROR_TIMEOUT) {
 			warnx("bulk write failed: %s", libusb_strerror(ret));
-			return -1;
+			return -EIO;
 		}
+		if (ret == LIBUSB_ERROR_TIMEOUT && actual == 0)
+			return -ETIMEDOUT;
 
 		count += actual;
 		len -= actual;
@@ -277,7 +278,7 @@ static int usb_write(struct qdl_device *qdl, const void *buf, size_t len)
 		ret = libusb_bulk_transfer(qdl_usb->usb_handle, qdl_usb->out_ep, NULL,
 					   0, &actual, 1000);
 		if (ret < 0)
-			return -1;
+			return -EIO;
 	}
 
 	return count;