MLK-9808 HDMI: EDID bug fixes / improvements

Changes in order of appearence:
- If an EDID extension block other than the known (CEA extension) is found
  don't fail monitor detection completely, just proceed to the next block.
- If 4 or more extensions are present two problems arise:
  - only 2 extensions will actually be read and
  - parsing will read beyond the buffer.
  Throw a BUG() and add a comment, don't have time for a rewrite right now.
- The EDID I2C read code has a 1 second timeout - per byte. With 128 bytes
  per block this could take over 2 minutes. And we have indeed seen a very
  long pause on Linux shutdown on rare occasions. At 100 kHz reading a byte
  takes 0.6 ms, reduce the timeout to 30 ms.
- Checking extblknum < 0 is pointless when its value was assigned from an
  unsigned char.
- Some old monitors didn't set the 'number of EDID ext. blocks' field. 0xFF
  means no extensions.
- Calling mxc_edid_parse_ext_blk() only makes sense if an ext. block was
  actually read. Otherwise it's sure to fail, and monitor detection with it.
- As the 1st extension was parsed beforehand the following for loop must
  start at 2, otherwise the 1st extension is parsed twice.
- Inside the read loop all bytes were written to tmpedid[1], It should
  tmpedid[i].
- And then when parsing the read data they have to start at tmpedid[0],
  not at tmpedid[EDID_LENGTH], which is beyond the buffer.
- Improved debugging a bit by inserting a message if reading fails and also
  removing one that may be confused with another with the same text.
- If getting the EDID data fails we will retry once. But if the failure was
  due to not being able to parse the data rather than a read error
  re-reading will yield HDMI_EDID_SAME. The code will misinterpret that as
  'no change, video modes already set up'. Instead continue with the status
  code of the initial attempt.
- Before retrying wait 0.2 s, most likely reading initially failed because
  the cable had not been fully inserted.

Signed-off-by: Sandor Yu <R01008@freescale.com>
(cherry picked from commit 1c580e028ebea180481b8539d3ee4264244a4ec6)

2 files changed, 28 insertions, 15 deletions

diff --git a/drivers/video/mxc/mxc_edid.c b/drivers/video/mxc/mxc_edid.c
index 88b52682d99b..d791bfea5609 100644
--- a/drivers/video/mxc/mxc_edid.c
+++ b/drivers/video/mxc/mxc_edid.c
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2013 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2009-2014 Freescale Semiconductor, Inc. All Rights Reserved.
  */
 
 /*
@@ -277,7 +277,7 @@ int mxc_edid_parse_ext_blk(unsigned char *edid,
 	int i, num = 0, revision;
 
 	if (edid[index++] != 0x2) /* only support cea ext block now */
-		return -1;
+		return 0;
 	revision = edid[index++];
 	DPRINTK("cea extent revision %d\n", revision);
 	mode = kzalloc(50 * sizeof(struct fb_videomode), GFP_KERNEL);
@@ -742,6 +742,10 @@ int mxc_edid_read(struct i2c_adapter *adp, unsigned short addr,
 	if (extblknum) {
 		int i;
 
+		/* FIXME: mxc_edid_readsegblk() won't read more than 2 blocks
+		 * and the for-loop will read past the end of the buffer! :-( */
+		BUG_ON(extblknum > 3);
+
 		/* need read segment block? */
 		if (extblknum > 1) {
 			ret = mxc_edid_readsegblk(adp, addr,
diff --git a/drivers/video/mxc/mxc_hdmi.c b/drivers/video/mxc/mxc_hdmi.c
index 51869988ff3c..2a816bc82658 100644
--- a/drivers/video/mxc/mxc_hdmi.c
+++ b/drivers/video/mxc/mxc_hdmi.c
@@ -937,7 +937,7 @@ static u8 hdmi_edid_i2c_read(struct mxc_hdmi *hdmi,
 		hdmi_writeb(HDMI_I2CM_OPERATION_READ_EXT,
 			HDMI_I2CM_OPERATION);
 
-	hdmi_edid_wait_i2c_done(hdmi, 1000);
+	hdmi_edid_wait_i2c_done(hdmi, 30);
 	data = hdmi_readb(HDMI_I2CM_DATAI);
 	hdmi_writeb(0xFF, HDMI_IH_I2CM_STAT0);
 	return data;
@@ -1563,8 +1563,8 @@ static int mxc_edid_read_internal(struct mxc_hdmi *hdmi, unsigned char *edid,
 	}
 
 	extblknum = edid[0x7E];
-	if (extblknum < 0)
-		return extblknum;
+	if (extblknum == 255)
+		extblknum = 0;
 
 	if (extblknum) {
 		ediddata = edid + EDID_LENGTH;
@@ -1578,19 +1578,21 @@ static int mxc_edid_read_internal(struct mxc_hdmi *hdmi, unsigned char *edid,
 	memset(&fbi->monspecs, 0, sizeof(fbi->monspecs));
 	fb_edid_to_monspecs(edid, &fbi->monspecs);
 
-	ret = mxc_edid_parse_ext_blk(edid + EDID_LENGTH,
-			cfg, &fbi->monspecs);
-	if (ret < 0)
-		return -ENOENT;
+	if (extblknum) {
+		ret = mxc_edid_parse_ext_blk(edid + EDID_LENGTH,
+				cfg, &fbi->monspecs);
+		if (ret < 0)
+			return -ENOENT;
+	}
 
 	/* need read segment block? */
 	if (extblknum > 1) {
-		for (j = 1; j <= extblknum; j++) {
+		for (j = 2; j <= extblknum; j++) {
 			for (i = 0; i < 128; i++)
-				*(tmpedid + 1) = hdmi_edid_i2c_read(hdmi, i, j);
+				tmpedid[i] = hdmi_edid_i2c_read(hdmi, i, j);
 
 			/* edid ext block parsing */
-			ret = mxc_edid_parse_ext_blk(tmpedid + EDID_LENGTH,
+			ret = mxc_edid_parse_ext_blk(tmpedid,
 					cfg, &fbi->monspecs);
 			if (ret < 0)
 				return -ENOENT;
@@ -1635,8 +1637,10 @@ static int mxc_hdmi_read_edid(struct mxc_hdmi *hdmi)
 		}
 
 	}
-	if (ret < 0)
+	if (ret < 0) {
+		dev_dbg(&hdmi->pdev->dev, "read failed\n");
 		return HDMI_EDID_FAIL;
+	}
 
 	/* Save edid cfg for audio driver */
 	hdmi_set_edid_cfg(&hdmi->edid_cfg);
@@ -1833,7 +1837,6 @@ static void  mxc_hdmi_default_modelist(struct mxc_hdmi *hdmi)
 	dev_dbg(&hdmi->pdev->dev, "%s\n", __func__);
 
 	/* If not EDID data read, set up default modelist  */
-	dev_info(&hdmi->pdev->dev, "No modes read from edid\n");
 	dev_info(&hdmi->pdev->dev, "create default modelist\n");
 
 	console_lock();
@@ -1919,8 +1922,14 @@ static void mxc_hdmi_cable_connected(struct mxc_hdmi *hdmi)
 	/* Read EDID again if first EDID read failed */
 	if (edid_status == HDMI_EDID_NO_MODES ||
 			edid_status == HDMI_EDID_FAIL) {
+		int retry_status;
 		dev_info(&hdmi->pdev->dev, "Read EDID again\n");
-		edid_status = mxc_hdmi_read_edid(hdmi);
+		msleep(200);
+		retry_status = mxc_hdmi_read_edid(hdmi);
+		/* If we get NO_MODES on the 1st and SAME on the 2nd attempt we
+		 * want NO_MODES as final result. */
+		if (retry_status != HDMI_EDID_SAME)
+			edid_status = retry_status;
 	}
 
 	/* HDMI Initialization Steps D, E, F */