From f7eb220401c161ad1c1a14cb1c34c6b2184ca862 Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@openmoko.org>
Date: Sun, 1 May 2011 15:08:02 -0300
Subject: [PATCH] ubb-vga: gently prepare the code for sharing mode information

This is tricky: if we just make "mode" global, the whole timing may
fall apart, with the DMA locking up. So let's take small bisectable
steps to get there ...

- ubb-vga.c (struct mode), ubb-vga.h: moved mode entry declaration to
  ubb-vga.h
- ubb-vga.c (mode_db): moved up
---
 ubb-vga/ubb-vga.c | 86 ++++++++++++++++++++++-------------------------
 ubb-vga/ubb-vga.h |  9 +++++
 2 files changed, 50 insertions(+), 45 deletions(-)

diff --git a/ubb-vga/ubb-vga.c b/ubb-vga/ubb-vga.c
index c768653..c1352a5 100644
--- a/ubb-vga/ubb-vga.c
+++ b/ubb-vga/ubb-vga.c
@@ -45,6 +45,47 @@ static volatile void *base;
 static int bad;
 
 
+#define	US(us)	((uint16_t) ((us)*112))
+
+
+static const struct mode mode_db[] = {
+    { "640x480",   640, 480, 11, US(29.7), US(0.79+3.77-0.3) },
+    { "800x600",   800, 600,  8, US(28.7), US(2.0+3.3+0.3) },
+    /* the next one may work after adjusting the timing in "frame" */
+    { "800x600",   800, 600,  8, US(28.2), US(2.0+3.3+0.3-0.3) },
+    /* the 1024x768 below is not great but has good parameter tolerance */
+    { "1024x768", 1024, 768,  8, US(36.0), US(2.0+3.3) },
+    /* illustrate underruns */
+    { "1024x768ur", 1024, 768, 7, US(33.5), US(0.4+2.1+0.5) },
+    { NULL }
+};
+
+	/*
+	 * Adjustment value tests with the XEN-1510 (640x480):
+	 *
+	 * Adjustment	Tries	Good	Jam	FIFO jitter
+	 *						Quick load
+	 * -0.0		10	3	7	0	n
+	 * -0.1		10	5	5	0	n
+	 * -0.2		10	6	4	0	n
+	 * -0.3		10	7	3	0	n
+	 *		10	5	5	0	y
+	 * -0.4		10	1	0	9	n
+	 * 		10	5	0	5	n	repeat
+	 *		10	5	0	5	y
+	 * -0.5		10	3	0	7	n
+	 * 		10	7	0	3	y
+	 * -1.0		 5	0	5	0
+	 *
+	 * Good = image is stable
+	 * Jam = does not detect the signal properly, loss of HSYNC, artefacts,
+	 *       or no image at all
+	 * FIFO jitter = some lines get shifted by a "digital" amount
+	 */
+
+static const struct mode *mode = mode_db;
+
+
 /* ----- I/O pin assignment ------------------------------------------------ */
 
 
@@ -172,9 +213,6 @@ static void cleanup(void)
 /* ----- Delay logic ------------------------------------------------------- */
 
 
-#define	US(us)	((uint16_t) ((us)*112))
-
-
 static void until(uint16_t cycles)
 {
 	while ((TCNT(TIMER) & 0xffff) < cycles);
@@ -184,48 +222,6 @@ static void until(uint16_t cycles)
 /* ----- Frame buffer output ----------------------------------------------- */
 
 
-static const struct mode {
-	const char *name;
-	int xres, yres;
-	int clkdiv;		/* pixel clock = 336 MHz/(clkdiv+1) */
-	int line_cycles;	/* 31.77 us for official VGA */
-	int hsync_end;		/* 0.79+3.77 us for official VGA */
-} mode_db[] = {
-    { "640x480",   640, 480, 11, US(29.7), US(0.79+3.77-0.3) },
-    { "800x600",   800, 600,  8, US(28.7), US(2.0+3.3+0.3) },
-    /* the next one may work after adjusting the timing in "frame" */
-    { "800x600",   800, 600,  8, US(28.2), US(2.0+3.3+0.3-0.3) },
-    /* the 1024x768 below is not great but has good parameter tolerance */
-    { "1024x768", 1024, 768,  8, US(36.0), US(2.0+3.3) },
-    /* illustrate underruns */
-    { "1024x768ur", 1024, 768, 7, US(33.5), US(0.4+2.1+0.5) },
-    { NULL }
-}, *mode = mode_db;
-
-	/*
-	 * Adjustment value tests with the XEN-1510 (640x480):
-	 *
-	 * Adjustment	Tries	Good	Jam	FIFO jitter
-	 *						Quick load
-	 * -0.0		10	3	7	0	n
-	 * -0.1		10	5	5	0	n
-	 * -0.2		10	6	4	0	n
-	 * -0.3		10	7	3	0	n
-	 *		10	5	5	0	y
-	 * -0.4		10	1	0	9	n
-	 * 		10	5	0	5	n	repeat
-	 *		10	5	0	5	y
-	 * -0.5		10	3	0	7	n
-	 * 		10	7	0	3	y
-	 * -1.0		 5	0	5	0
-	 *
-	 * Good = image is stable
-	 * Jam = does not detect the signal properly, loss of HSYNC, artefacts,
-	 *       or no image at all
-	 * FIFO jitter = some lines get shifted by a "digital" amount
-	 */
-
-
 static void setup(void)
 {
 	mlockall(MCL_CURRENT | MCL_FUTURE);
diff --git a/ubb-vga/ubb-vga.h b/ubb-vga/ubb-vga.h
index 67b7db3..824d2e0 100644
--- a/ubb-vga/ubb-vga.h
+++ b/ubb-vga/ubb-vga.h
@@ -23,6 +23,15 @@
 #define	Y_VAL	(1 << 2)
 
 
+struct mode {
+	const char *name;	/* NULL for end of table */
+	int xres, yres;
+	int clkdiv;		/* pixel clock = 336 MHz/(clkdiv+1) */
+	int line_cycles;	/* 31.77 us for official VGA */
+	int hsync_end;		/* 0.79+3.77 us for official VGA */
+};
+
+
 void *map(off_t addr, size_t size);