From 4729d00b30ff7c0224337217f65496c86b8df75d Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Wed, 16 Jan 2013 03:56:17 -0300
Subject: [PATCH] ubb-patgen/ubb-patgen.c: run at realtime priority while
 waiting for trigger

---
 ubb-patgen/ubb-patgen.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/ubb-patgen/ubb-patgen.c b/ubb-patgen/ubb-patgen.c
index 00d33ac..863d534 100644
--- a/ubb-patgen/ubb-patgen.c
+++ b/ubb-patgen/ubb-patgen.c
@@ -18,6 +18,7 @@
 #include <string.h>
 #include <math.h>
 #include <time.h>
+#include <sched.h>
 #include <assert.h>
 #include <sys/mman.h>
 
@@ -248,6 +249,36 @@ static const char *load_pattern(const char *s)
 }
 
 
+/* ----- Real-time mode ---------------------------------------------------- */
+
+
+void realtimize(void)
+{
+	struct sched_param prm;
+
+	prm.sched_priority = sched_get_priority_max(SCHED_FIFO);
+	if (prm.sched_priority < 0) {
+		perror("sched_get_priority_max SCHED_FIFO");
+		exit(1);
+	}
+	if (sched_setscheduler(0, SCHED_FIFO, &prm) < 0) {
+		perror("sched_setscheduler SCHED_FIFO");
+		exit(1);
+	}
+}
+
+
+void unrealtime(void)
+{
+	struct sched_param prm = { .sched_priority = 0 };
+
+	if (sched_setscheduler(0, SCHED_OTHER, &prm) < 0) {
+		perror("sched_setscheduler SCHED_OTHER");
+		exit(1);
+	}
+}
+
+
 /* ----- DMA control ------------------------------------------------------- */
 
 
@@ -409,6 +440,8 @@ static void mmc_buffer(const struct mmcclk *clk,
 
 	PDFUNS = mask;
 
+	realtimize();
+
 	if (trigger != -1)
 		wait_trigger(trigger, debounce, debounce_ns);
 	if (wait_ns->tv_sec || wait_ns->tv_nsec)
@@ -425,6 +458,8 @@ static void mmc_buffer(const struct mmcclk *clk,
 	    (1 << 31) |         /* no descriptor */
 	    1;			/* enable transfer */
 
+	unrealtime();
+
 	wait_dma_done();
 	wait_fifo_empty();
 	wait_shifted(clk);