From: Nickey Yang <nickey.yang@rock-chips.com>
Date: Thu, 9 Mar 2017 02:56:37 +0000 (+0800)
Subject: FROMLIST: drm/bridge: dw_hdmi: support i2c extended read mode
X-Git-Tag: firefly_0821_release~385
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=7d8946a76eba5578c0160bea81b385bb794cf072;p=firefly-linux-kernel-4.4.55.git

FROMLIST: drm/bridge: dw_hdmi: support i2c extended read mode

"I2C Master Interface Extended Read Mode" implements a segment
pointer-based read operation using the Special Register configuration.

This patch fix https://patchwork.kernel.org/patch/7098101/ mentioned
"The current implementation does not support "I2C Master Interface
Extended Read Mode" to read data addressed by non-zero segment
pointer, this means that if EDID has more than 1 extension blocks"

With this patch,dw-hdmi can read EDID data with 1/2/4 blocks.

(am from https://patchwork.kernel.org/patch/9586343/)

BUG=chrome-os-partner:59768
TEST=fievel can read 1/2/4 blocks EDID data

Change-Id: I086e6ea63ec69c0532be445b958ce253a7f1f3cc
Signed-off-by: Nickey Yang <nickey.yang@rock-chips.com>
Reviewed-on: https://chromium-review.googlesource.com/442308
Reviewed-by: Douglas Anderson <dianders@chromium.org>
---

diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
index feb4dcb45d2c..e9eb6d5ca7d7 100644
--- a/drivers/gpu/drm/bridge/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/dw-hdmi.c
@@ -39,6 +39,7 @@
 #include "dw-hdmi-audio.h"
 
 #define HDMI_EDID_LEN		512
+#define DDC_SEGMENT_ADDR       0x30
 
 #define RGB			0
 #define YCBCR444		1
@@ -174,6 +175,7 @@ struct dw_hdmi_i2c {
 
 	u8			slave_reg;
 	bool			is_regaddr;
+	bool			is_segment;
 };
 
 struct dw_hdmi {
@@ -317,8 +319,12 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi,
 		reinit_completion(&i2c->cmp);
 
 		hdmi_writeb(hdmi, i2c->slave_reg++, HDMI_I2CM_ADDRESS);
-		hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ,
-			    HDMI_I2CM_OPERATION);
+		if (i2c->is_segment)
+			hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ_EXT,
+				    HDMI_I2CM_OPERATION);
+		else
+			hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ,
+				    HDMI_I2CM_OPERATION);
 
 		stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10);
 		if (!stat)
@@ -330,6 +336,7 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi,
 
 		*buf++ = hdmi_readb(hdmi, HDMI_I2CM_DATAI);
 	}
+	i2c->is_segment = false;
 
 	return 0;
 }
@@ -379,12 +386,6 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
 	dev_dbg(hdmi->dev, "xfer: num: %d, addr: %#x\n", num, addr);
 
 	for (i = 0; i < num; i++) {
-		if (msgs[i].addr != addr) {
-			dev_warn(hdmi->dev,
-				 "unsupported transfer, changed slave address\n");
-			return -EOPNOTSUPP;
-		}
-
 		if (msgs[i].len == 0) {
 			dev_dbg(hdmi->dev,
 				"unsupported transfer %d/%d, no data\n",
@@ -403,15 +404,24 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
 	/* Set slave device register address on transfer */
 	i2c->is_regaddr = false;
 
+	/* Set segment pointer for I2C extended read mode operation */
+	i2c->is_segment = false;
+
 	for (i = 0; i < num; i++) {
 		dev_dbg(hdmi->dev, "xfer: num: %d/%d, len: %d, flags: %#x\n",
 			i + 1, num, msgs[i].len, msgs[i].flags);
-
-		if (msgs[i].flags & I2C_M_RD)
-			ret = dw_hdmi_i2c_read(hdmi, msgs[i].buf, msgs[i].len);
-		else
-			ret = dw_hdmi_i2c_write(hdmi, msgs[i].buf, msgs[i].len);
-
+		if (msgs[i].addr == DDC_SEGMENT_ADDR && msgs[i].len == 1) {
+			i2c->is_segment = true;
+			hdmi_writeb(hdmi, DDC_SEGMENT_ADDR, HDMI_I2CM_SEGADDR);
+			hdmi_writeb(hdmi, *msgs[i].buf, HDMI_I2CM_SEGPTR);
+		} else {
+			if (msgs[i].flags & I2C_M_RD)
+				ret = dw_hdmi_i2c_read(hdmi, msgs[i].buf,
+						       msgs[i].len);
+			else
+				ret = dw_hdmi_i2c_write(hdmi, msgs[i].buf,
+							msgs[i].len);
+		}
 		if (ret < 0)
 			break;
 	}