msm: mdss: dp: fix EDID read sequence

Update the EDID read sequence to first write the offset to
request the appropriate EDID block prior to reading the EDID
block data. In addition, write the correct segment address
when reading more than two extension blocks.

CRs-Fixed: 2006096
Change-Id: Ic4b2bd4d4cf9da5e247c5735b4e768b9e2b87b27
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>

1 files changed, 45 insertions, 13 deletions

diff --git a/drivers/video/fbdev/msm/mdss_dp_aux.c b/drivers/video/fbdev/msm/mdss_dp_aux.c
index 671ca8270e4c..eb1cb8785621 100644
--- a/drivers/video/fbdev/msm/mdss_dp_aux.c
+++ b/drivers/video/fbdev/msm/mdss_dp_aux.c
@@ -876,10 +876,10 @@ int mdss_dp_edid_read(struct mdss_dp_drv_pdata *dp)
 	int rlen, ret = 0;
 	int edid_blk = 0, blk_num = 0, retries = 10;
 	bool edid_parsing_done = false;
-	const u8 cea_tag = 0x02, start_ext_blk = 0x1;
+	const u8 cea_tag = 0x02;
 	u32 const segment_addr = 0x30;
 	u32 checksum = 0;
-	char segment = 0x1;
+	u8 offset[] = {0x0, 0x80};
 
 	ret = dp_aux_chan_ready(dp);
 	if (ret) {
@@ -895,26 +895,56 @@ int mdss_dp_edid_read(struct mdss_dp_drv_pdata *dp)
 	 */
 	dp_sink_parse_test_request(dp);
 
-	do {
-		rlen = dp_aux_read_buf_retry(dp, EDID_START_ADDRESS +
-				(blk_num * EDID_BLOCK_SIZE),
+	while (retries) {
+		u8 *offset_p;
+		u8 segment;
+
+		/*
+		 * Write the segment first.
+		 * Segment = 0, for blocks 0 and 1
+		 * Segment = 1, for blocks 2 and 3
+		 * Segment = 2, for blocks 3 and 4
+		 * and so on ...
+		 */
+		segment = blk_num >> 1;
+		dp_aux_write_buf_retry(dp, segment_addr, &segment, 1, 1, false);
+
+		/*
+		 * Write the offset of the desired EDID block to be read.
+		 * For even blocks, offset = 0x0
+		 * For odd blocks, offset = 0x80
+		 */
+		if (blk_num % 2)
+			offset_p = &offset[1];
+		else
+			offset_p = &offset[0];
+		dp_aux_write_buf_retry(dp, EDID_START_ADDRESS, offset_p, 1, 1,
+				false);
+
+		rlen = dp_aux_read_buf_retry(dp, EDID_START_ADDRESS,
 				EDID_BLOCK_SIZE, 1, false);
 		if (rlen != EDID_BLOCK_SIZE) {
-			pr_err("Read failed. rlen=%d\n", rlen);
+			pr_err("Read failed. rlen=%s\n",
+				mdss_dp_get_aux_error(rlen));
+			mdss_dp_phy_aux_update_config(dp, PHY_AUX_CFG1);
+			retries--;
 			continue;
 		}
-
 		pr_debug("blk_num=%d, rlen=%d\n", blk_num, rlen);
 
 		if (dp_edid_is_valid_header(rp->data)) {
 			ret = dp_edid_buf_error(rp->data, rp->len);
 			if (ret) {
 				pr_err("corrupt edid block detected\n");
+				mdss_dp_phy_aux_update_config(dp, PHY_AUX_CFG1);
+				retries--;
 				continue;
 			}
 
 			if (edid_parsing_done) {
+				pr_debug("block 0 parsed already\n");
 				blk_num++;
+				retries--;
 				continue;
 			}
 
@@ -928,6 +958,12 @@ int mdss_dp_edid_read(struct mdss_dp_drv_pdata *dp)
 				rp->data);
 
 			edid_parsing_done = true;
+		} else if (!edid_parsing_done) {
+			pr_debug("Invalid edid block 0 header\n");
+			/* Retry block 0 with adjusted phy aux settings */
+			mdss_dp_phy_aux_update_config(dp, PHY_AUX_CFG1);
+			retries--;
+			continue;
 		} else {
 			edid_blk++;
 			blk_num++;
@@ -948,13 +984,9 @@ int mdss_dp_edid_read(struct mdss_dp_drv_pdata *dp)
 		checksum = rp->data[rp->len - 1];
 
 		/* break if no more extension blocks present */
-		if (edid_blk == dp->edid.ext_block_cnt)
+		if (edid_blk >= dp->edid.ext_block_cnt)
 			break;
-
-		/* write segment number to read block 3 onwards */
-		if (edid_blk == start_ext_blk)
-			dp_aux_write_buf(dp, segment_addr, &segment, 1, 1);
-	} while (retries--);
+	}
 
 	if (dp->test_data.test_requested == TEST_EDID_READ) {
 		pr_debug("sending checksum %d\n", checksum);