On Mon, 02 Feb 2026, Nilesh Laad <[email protected]> wrote:
> 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(<9611uxc->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(<9611uxc->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,
> + <9611uxc->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 you want caching, you should cache the result of
drm_edid_read_custom() at lt9611uxc_bridge_edid_read(). I don't see the
point of having a separate array for this.
Please just try to provide a mechanism to read one block for
drm_edid_read_custom() instead of adding completely separate logic and
then memcpying that.
> + if (lt9611uxc->edid_available && (block < lt9611uxc->num_edid_blocks))
> + memcpy(buf, <9611uxc->edid_raw[EDID_BLOCK_SIZE*block],
> EDID_BLOCK_SIZE);
While it is true that drm_edid.c *currently* only passes EDID_BLOCK_SIZE
for len, it's bad form to not respect the passed in len parameter.
BR,
Jani.
> + 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(<9611uxc->edid_raw[block*EDID_BLOCK_SIZE],
> +
> <9611uxc->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,
> <9611uxc->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]>
>
--
Jani Nikula, Intel
