[Jack-Devel] [PATCH] v1.2 of setbufsize support for firewire driver

Hi again

Another day, another tweak to the ffado setbufsize patch.  This is version
1.2.  Differences from version 1.1:

 - be more liberal in accepting libffado API version numbers.
 - patch confirmed to apply cleanly to current jack svn (r4778).

Regards
  jonathan

--- jack-orig/drivers/firewire/ffado_driver.c	2012-03-13 14:47:43.042406524 +1030
+++ jack/drivers/firewire/ffado_driver.c	2012-03-13 15:36:43.181078985 +1030
@@ -7,6 +7,7 @@
  *   http://www.jackaudio.org
  *
  *   Copyright (C) 2005-2007 Pieter Palmers
+ *   Copyright (C) 2012 Jonathan Woithe
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -50,7 +51,10 @@
 
 static int ffado_driver_stop (ffado_driver_t *driver);
 
+// Basic functionality requires API version 8.  If version 9 or later
+// is present the buffers can be resized at runtime.
 #define FIREWIRE_REQUIRED_FFADO_API_VERSION 8
+#define FIREWIRE_REQUIRED_FFADO_API_VERSION_FOR_SETBUFSIZE 9
 
 // enable verbose messages
 static int g_verbose=0;
@@ -675,24 +679,71 @@
 static int
 ffado_driver_bufsize (ffado_driver_t* driver, jack_nframes_t nframes)
 {
-	printError("Buffer size change requested but not supported!!!");
+	signed int chn;
 
-	/*
-	 driver->period_size = nframes;  
+	// The speed of this function isn't critical; we can afford the
+	// time to check the FFADO API version.
+	if (ffado_get_api_version() < FIREWIRE_REQUIRED_FFADO_API_VERSION_FOR_SETBUFSIZE ||
+            ffado_streaming_set_period_size == NULL) {
+	        printError("unsupported on current version of FFADO; please upgrade FFADO");
+	        return -1;
+	}
+
+	driver->period_size = nframes;  
 	driver->period_usecs =
 		(jack_time_t) floor ((((float) nframes) / driver->sample_rate)
 				     * 1000000.0f);
-	*/
-	
+
+	// Reallocate the null and scratch buffers.
+	driver->nullbuffer = calloc(driver->period_size, sizeof(ffado_sample_t));
+	if(driver->nullbuffer == NULL) {
+		printError("could not allocate memory for null buffer");
+		return -1;
+	}
+	driver->scratchbuffer = calloc(driver->period_size, sizeof(ffado_sample_t));
+	if(driver->scratchbuffer == NULL) {
+		printError("could not allocate memory for scratch buffer");
+		return -1;
+	}
+
+	// MIDI buffers need reallocating
+	for (chn = 0; chn < driver->capture_nchannels; chn++) {
+		if(driver->capture_channels[chn].stream_type == ffado_stream_type_midi) {
+			// setup the midi buffer
+			if (driver->capture_channels[chn].midi_buffer != NULL)
+			        free(driver->capture_channels[chn].midi_buffer);
+			driver->capture_channels[chn].midi_buffer = calloc(driver->period_size, sizeof(uint32_t));
+		}
+	}
+	for (chn = 0; chn < driver->playback_nchannels; chn++) {
+		if(driver->playback_channels[chn].stream_type == ffado_stream_type_midi) {
+		        if (driver->playback_channels[chn].midi_buffer != NULL)
+		                free(driver->playback_channels[chn].midi_buffer);
+			driver->playback_channels[chn].midi_buffer = calloc(driver->period_size, sizeof(uint32_t));
+		}
+	}
+
+	// Notify FFADO of the period size change
+	if (ffado_streaming_set_period_size(driver->dev, nframes) != 0) {
+	        printError("could not alter FFADO device period size");
+	        return -1;
+	}
+
+	// This is needed to give the shadow variables a chance to
+	// properly update to the changes.
+	sleep(1);
+
 	/* tell the engine to change its buffer size */
-#if 0
 	if (driver->engine->set_buffer_size (driver->engine, nframes)) {
 		jack_error ("FFADO: cannot set engine buffer size to %d (check MIDI)", nframes);
 		return -1;
 	}
-#endif
 
-	return -1; // unsupported
+	// Other drivers (eg: ALSA) don't seem to adjust latencies via
+	// jack_port_set_latency_range() from the bufsize() callback, so we
+	// won't either.  Is this right?
+
+        return 0;
 }
 
 typedef void (*JackDriverFinishFunction) (jack_driver_t *);
@@ -704,7 +755,7 @@
 {
 	ffado_driver_t *driver;
 
-	if(ffado_get_api_version() != FIREWIRE_REQUIRED_FFADO_API_VERSION) {
+	if(ffado_get_api_version() < FIREWIRE_REQUIRED_FFADO_API_VERSION) {
 		printError("Incompatible libffado version! (%s)", ffado_get_version());
 		return NULL;
 	}

1331615603.27558_0.ltw:2, <20120313051303.GL14630 at marvin dot atrad dot com dot au>