[PATCH v2 1/2] drm: bridge: adv7511: fix reading edid segments

[Emil Abildgaard Svendsen]

Currently reading EDID only works because usually only two EDID blocks
of 128 bytes is used. Where an EDID segment holds 256 bytes or two EDID
blocks. And the first EDID segment read works fine but E-EDID specifies
up to 128 segments.

The logic is broken so change EDID segment index to multiple of 256
bytes and not 128 (block size).

Fixes: 9c8af882bf12 ("drm: Add adv7511 encoder driver")

Signed-off-by: Emil Svendsen <emas at bang-olufsen.dk>
---
v2:
 - Split into two patches.
 - Add Fixes tag.

v1: https://lore.kernel.org/all/20231026113029.575846-1-emas@bang-olufsen.dk/

 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 8be235144f6d..9b6294120516 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -537,6 +537,7 @@ static int adv7511_get_edid_block(void *data, u8 *buf, unsigned int block,
 				  size_t len)
 {
 	struct adv7511 *adv7511 = data;
+	int edid_segment = block / 2;
 	struct i2c_msg xfer[2];
 	uint8_t offset;
 	unsigned int i;
@@ -545,7 +546,7 @@ static int adv7511_get_edid_block(void *data, u8 *buf, unsigned int block,
 	if (len > 128)
 		return -EINVAL;
 
-	if (adv7511->current_edid_segment != block / 2) {
+	if (adv7511->current_edid_segment != edid_segment) {
 		unsigned int status;
 
 		ret = regmap_read(adv7511->regmap, ADV7511_REG_DDC_STATUS,
@@ -556,7 +557,7 @@ static int adv7511_get_edid_block(void *data, u8 *buf, unsigned int block,
 		if (status != 2) {
 			adv7511->edid_read = false;
 			regmap_write(adv7511->regmap, ADV7511_REG_EDID_SEGMENT,
-				     block);
+				     edid_segment);
 			ret = adv7511_wait_for_edid(adv7511, 200);
 			if (ret < 0)
 				return ret;
@@ -589,7 +590,7 @@ static int adv7511_get_edid_block(void *data, u8 *buf, unsigned int block,
 			offset += 64;
 		}
 
-		adv7511->current_edid_segment = block / 2;
+		adv7511->current_edid_segment = edid_segment;
 	}
 
 	if (block % 2 == 0)
-- 
2.34.1