From: Ravi Agola <[email protected]>

The lt9611uxc driver previously limited EDID reading to 2 blocks, which
restricted support for displays that provide more than two EDID blocks.
This change enables the driver to read and pass up to 4 EDID blocks from
the LT9611UXC to drm_edid calls.
As a result, the driver now supports displays with up to 4 EDID block.

Signed-off-by: Ravi Agola <[email protected]>
Signed-off-by: Nilesh Laad <[email protected]>
---
 drivers/gpu/drm/bridge/lontium-lt9611uxc.c | 93 ++++++++++++++++++++++++++----
 1 file changed, 82 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt9611uxc.c 
b/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
index 4d989381904c..7fe481c7acf8 100644
--- a/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
+++ b/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
@@ -28,7 +28,7 @@
 #include <drm/display/drm_hdmi_audio_helper.h>
 
 #define EDID_BLOCK_SIZE        128
-#define EDID_NUM_BLOCKS        2
+#define EDID_NUM_BLOCKS        4
 
 #define FW_FILE "lt9611uxc_fw.bin"
 
@@ -61,6 +61,11 @@ struct lt9611uxc {
        /* can be accessed from different threads, so protect this with 
ocm_lock */
        bool hdmi_connected;
        uint8_t fw_version;
+
+       bool edid_available;
+       unsigned int num_edid_blocks;
+       uint8_t edid_raw[EDID_BLOCK_SIZE * EDID_NUM_BLOCKS];
+
 };
 
 #define LT9611_PAGE_CONTROL    0xff
@@ -170,8 +175,12 @@ static void lt9611uxc_hpd_work(struct work_struct *work)
        connected = lt9611uxc->hdmi_connected;
        mutex_unlock(&lt9611uxc->ocm_lock);
 
-       if (!connected)
+       if (!connected) {
                lt9611uxc->edid_read = false;
+               lt9611uxc->edid_available = false;
+               lt9611uxc->num_edid_blocks = 0;
+               memset(lt9611uxc->edid_raw, 0, EDID_BLOCK_SIZE * 
EDID_NUM_BLOCKS);
+       }
 
        drm_bridge_hpd_notify(&lt9611uxc->bridge,
                              connected ?
@@ -387,10 +396,32 @@ static int lt9611uxc_wait_for_edid(struct lt9611uxc 
*lt9611uxc)
                        msecs_to_jiffies(500));
 }
 
+static int lt9611uxc_read_edid_block(struct lt9611uxc *lt9611uxc, unsigned int 
block)
+{
+       int ret;
+
+       lt9611uxc_lock(lt9611uxc);
+
+       regmap_write(lt9611uxc->regmap, 0xb00a, (block%2) * EDID_BLOCK_SIZE);
+
+       ret = regmap_noinc_read(lt9611uxc->regmap, 0xb0b0,
+                       &lt9611uxc->edid_raw[block*EDID_BLOCK_SIZE], 
EDID_BLOCK_SIZE);
+       if (ret) {
+               dev_err(lt9611uxc->dev, "edid block %d read failed: %d\n", 
block, ret);
+               lt9611uxc_unlock(lt9611uxc);
+               return -EINVAL;
+       }
+       lt9611uxc_unlock(lt9611uxc);
+
+       return ret;
+}
+
 static int lt9611uxc_get_edid_block(void *data, u8 *buf, unsigned int block, 
size_t len)
 {
        struct lt9611uxc *lt9611uxc = data;
-       int ret;
+       int ret = 0;
+       int retry_cnt = 10;
+       int edid_ext_block;
 
        if (len > EDID_BLOCK_SIZE)
                return -EINVAL;
@@ -398,19 +429,59 @@ static int lt9611uxc_get_edid_block(void *data, u8 *buf, 
unsigned int block, siz
        if (block >= EDID_NUM_BLOCKS)
                return -EINVAL;
 
-       lt9611uxc_lock(lt9611uxc);
+       /*
+        * if edid is read once, provide same edid data till next hpd event
+        */
+       if (lt9611uxc->edid_available && (block < lt9611uxc->num_edid_blocks))
+               memcpy(buf, &lt9611uxc->edid_raw[EDID_BLOCK_SIZE*block], 
EDID_BLOCK_SIZE);
+       else {
+               /*
+                * read number of block available in edid data
+                */
+               if (block == 0) {
+                       lt9611uxc_lock(lt9611uxc);
+                       ret = regmap_read(lt9611uxc->regmap, 0xb02a, 
&edid_ext_block);
+                       if (ret)
+                               dev_err(lt9611uxc->dev, "edid block read 
failed: %d\n", ret);
+                       else
+                               lt9611uxc->num_edid_blocks = edid_ext_block & 
0x7;
+                       lt9611uxc_unlock(lt9611uxc);
+               }
 
-       regmap_write(lt9611uxc->regmap, 0xb00b, 0x10);
+               /* read edid block */
+               ret = lt9611uxc_read_edid_block(lt9611uxc, block);
+
+               /* compare first 4 bytes of 0th and 2nd block to confirm
+                * that 2nd edid block data is read successfully by lt9611uxc
+                */
+               while ((block == 2) && 0 == 
memcmp(&lt9611uxc->edid_raw[block*EDID_BLOCK_SIZE],
+                               
&lt9611uxc->edid_raw[(block%2)*EDID_BLOCK_SIZE], 4)
+                                               && retry_cnt-- > 0) {
+                       msleep(100);
+                       ret = lt9611uxc_read_edid_block(lt9611uxc, block);
+               }
 
-       regmap_write(lt9611uxc->regmap, 0xb00a, block * EDID_BLOCK_SIZE);
+               /* if more than 2 edid block are available, reset edid ready
+                * flag once 0th and 1st edid block read is completed
+                * so lt9611uxc read 2nd and 3rd block
+                */
+               if (block == 1 && lt9611uxc->num_edid_blocks > 2) {
+                       lt9611uxc_lock(lt9611uxc);
+                       regmap_write(lt9611uxc->regmap, 0xb02a, (edid_ext_block 
& (~BIT(3))));
+                       lt9611uxc_unlock(lt9611uxc);
+                       msleep(100);
+               }
 
-       ret = regmap_noinc_read(lt9611uxc->regmap, 0xb0b0, buf, len);
-       if (ret)
-               dev_err(lt9611uxc->dev, "edid read failed: %d\n", ret);
+               /* set edid available to true once all edid blocks read 
successfully */
+               if (block == (lt9611uxc->num_edid_blocks-1) && ret == 0)
+                       lt9611uxc->edid_available = true;
 
-       lt9611uxc_unlock(lt9611uxc);
+               /* copy edid block data into buffer */
+               if (ret == 0)
+                       memcpy(buf, 
&lt9611uxc->edid_raw[EDID_BLOCK_SIZE*block], EDID_BLOCK_SIZE);
+       }
 
-       return 0;
+       return ret;
 };
 
 static const struct drm_edid *lt9611uxc_bridge_edid_read(struct drm_bridge 
*bridge,

---
base-commit: 3ea699b56d31c2a5140d9fac309ff5e0f2041411
change-id: 20260202-extend-edid-support-b5a4f76d1832
prerequisite-message-id: 
[email protected]
prerequisite-patch-id: bbe63ef7dc85903a286cefd9aa09f1e2e96351b1

Best regards,
--  
Nilesh Laad <[email protected]>

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