From 28401b25cc5c1afb272e506cef196ba3a1258bd3 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Thu, 30 Nov 2006 15:45:13 -0800
Subject: Add debug code for the bit-banging I2C implementation.

---
 src/i830_i2c.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/src/i830_i2c.c b/src/i830_i2c.c
index 8b93c8e6..ea828ffb 100644
--- a/src/i830_i2c.c
+++ b/src/i830_i2c.c
@@ -273,12 +273,51 @@ i830I2CGetBits(I2CBusPtr b, int *clock, int *data)
     *clock = (val & GPIO_CLOCK_VAL_IN) != 0;
 }
 
+#define I2C_DEBUG 0
+
+#if I2C_DEBUG
+static int last_clock = 0, last_data = 0;
+static Bool first = TRUE;
+#endif
+
 static void
 i830I2CPutBits(I2CBusPtr b, int clock, int data)
 {
+#if I2C_DEBUG
+    int cur_clock, cur_data;
+    char *debug = "";
+#endif
+
     ScrnInfoPtr pScrn = xf86Screens[b->scrnIndex];
     I830Ptr pI830 = I830PTR(pScrn);
 
+#if I2C_DEBUG
+    if (!first && cur_clock != last_clock && cur_data != last_data) {
+	/* If we change the clock and data simultaneously, that would be bad.
+	 * I thought we did sometimes, but maybe not.
+	 */
+	debug = " <--";
+    }
+
+    last_clock = cur_clock;
+    last_data = cur_data;
+
+    i830I2CGetBits(b, &cur_clock, &cur_data);
+
+    if (first) {
+	ErrorF("I2C Debug:        C D      C D\n");
+	first = FALSE;
+    }
+
+    ErrorF("Setting I2C 0x%08x to: %c %c (at: %c %c)%s\n",
+	   b->DriverPrivate.uval,
+	   clock ? '^' : 'v',
+	   data ? '^' : 'v',
+	   cur_clock ? '^' : 'v',
+	   cur_data ? '^' : 'v',
+	   debug);
+#endif
+
     OUTREG(b->DriverPrivate.uval,
 	(data ? GPIO_DATA_VAL_OUT : 0) |
 	(clock ? GPIO_CLOCK_VAL_OUT : 0) |
-- 
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