video: exynos_dp: Improve EDID error handling

EDID error handling has 2 problems:
 - It doesn't fail as early as it can
 - The retry counts for i2c and aux transactions are huge

This patch fails if the initial i2c transaction fails, and reduces the
aux and i2c retry counts down to 3.

[jg1.han@samsung.com: reduced the retry count of exynos_dp_read_byte_from_dpcd()]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Jingoo Han <jg1.han@samsung.com>

2 files changed, 14 insertions, 13 deletions

diff --git a/drivers/video/exynos/exynos_dp_core.c b/drivers/video/exynos/exynos_dp_core.c
index d60f8da720d1..a4c1dec763bd 100644
--- a/drivers/video/exynos/exynos_dp_core.c
+++ b/drivers/video/exynos/exynos_dp_core.c
@@ -91,9 +91,11 @@ static int exynos_dp_read_edid(struct exynos_dp_device *dp)
          */
 
         /* Read Extension Flag, Number of 128-byte EDID extension blocks */
-        exynos_dp_read_byte_from_i2c(dp, I2C_EDID_DEVICE_ADDR,
+        retval = exynos_dp_read_byte_from_i2c(dp, I2C_EDID_DEVICE_ADDR,
                                 EDID_EXTENSION_FLAG,
                                 &extend_block);
+        if (retval)
+                return retval;
 
         if (extend_block > 0) {
                 dev_dbg(dp->dev, "EDID data includes a single extension!\n");
@@ -182,14 +184,15 @@ static int exynos_dp_handle_edid(struct exynos_dp_device *dp)
         int retval;
 
         /* Read DPCD DPCD_ADDR_DPCD_REV~RECEIVE_PORT1_CAP_1 */
-        exynos_dp_read_bytes_from_dpcd(dp,
-                DPCD_ADDR_DPCD_REV,
-                12, buf);
+        retval = exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_DPCD_REV,
+                                12, buf);
+        if (retval)
+                return retval;
 
         /* Read EDID */
         for (i = 0; i < 3; i++) {
                 retval = exynos_dp_read_edid(dp);
-                if (retval == 0)
+                if (!retval)
                         break;
         }
 
diff --git a/drivers/video/exynos/exynos_dp_reg.c b/drivers/video/exynos/exynos_dp_reg.c
index 3f5ca8a0d5ea..fc19ef651565 100644
--- a/drivers/video/exynos/exynos_dp_reg.c
+++ b/drivers/video/exynos/exynos_dp_reg.c
@@ -491,7 +491,7 @@ int exynos_dp_read_byte_from_dpcd(struct exynos_dp_device *dp,
         int i;
         int retval;
 
-        for (i = 0; i < 10; i++) {
+        for (i = 0; i < 3; i++) {
                 /* Clear AUX CH data buffer */
                 reg = BUF_CLR;
                 writel(reg, dp->reg_base + EXYNOS_DP_BUFFER_DATA_CTL);
@@ -552,7 +552,7 @@ int exynos_dp_write_bytes_to_dpcd(struct exynos_dp_device *dp,
                 else
                         cur_data_count = count - start_offset;
 
-                for (i = 0; i < 10; i++) {
+                for (i = 0; i < 3; i++) {
                         /* Select DPCD device address */
                         reg = AUX_ADDR_7_0(reg_addr + start_offset);
                         writel(reg, dp->reg_base + EXYNOS_DP_AUX_ADDR_7_0);
@@ -617,7 +617,7 @@ int exynos_dp_read_bytes_from_dpcd(struct exynos_dp_device *dp,
                         cur_data_count = count - start_offset;
 
                 /* AUX CH Request Transaction process */
-                for (i = 0; i < 10; i++) {
+                for (i = 0; i < 3; i++) {
                         /* Select DPCD device address */
                         reg = AUX_ADDR_7_0(reg_addr + start_offset);
                         writel(reg, dp->reg_base + EXYNOS_DP_AUX_ADDR_7_0);
@@ -700,17 +700,15 @@ int exynos_dp_read_byte_from_i2c(struct exynos_dp_device *dp,
         int i;
         int retval;
 
-        for (i = 0; i < 10; i++) {
+        for (i = 0; i < 3; i++) {
                 /* Clear AUX CH data buffer */
                 reg = BUF_CLR;
                 writel(reg, dp->reg_base + EXYNOS_DP_BUFFER_DATA_CTL);
 
                 /* Select EDID device */
                 retval = exynos_dp_select_i2c_device(dp, device_addr, reg_addr);
-                if (retval != 0) {
-                        dev_err(dp->dev, "Select EDID device fail!\n");
+                if (retval != 0)
                         continue;
-                }
 
                 /*
                  * Set I2C transaction and read data
@@ -750,7 +748,7 @@ int exynos_dp_read_bytes_from_i2c(struct exynos_dp_device *dp,
         int retval = 0;
 
         for (i = 0; i < count; i += 16) {
-                for (j = 0; j < 100; j++) {
+                for (j = 0; j < 3; j++) {
                         /* Clear AUX CH data buffer */
                         reg = BUF_CLR;
                         writel(reg, dp->reg_base + EXYNOS_DP_BUFFER_DATA_CTL);