Re: [PATCH V3 4/4] drm/bridge: it66121: Add minimal it66122 support

[Andrew Davis <afd@ti.com>]

On 8/14/25 10:41 PM, Nishanth Menon wrote:
> The IT66122 is a pin compatible replacement for the IT66122. Based on
> empirical testing, the new device looks to be compatible with IT66121.
> However due to a lack of public data sheet at this time beyond overall
> feature list[1] (which seems to add additional features vs ITT66121),
> it is hard to determine that additional register operations required
> to enable additional features.
> 
> So, introduce the device as a new compatible that we will detect based
> on vid/pid match, with explicit id that can be used to extend the
> driver capability as information becomes available later on.
> 
> [1] https://www.ite.com.tw/en/product/cate1/IT66122
> 
> Signed-off-by: Nishanth Menon <nm@ti.com>
> ---
> Changes in V3:
> * Dropped the claim that it is 1-1 replacement of IT66121.
> * Based on emperical test result[2], introduce the same configuration of
>    IT66121, but provide ID as suggested by Devarsh to allow for future
>    expansion of functionality.
> 
> NOTE: I did consider the possibility of converting the chip_id into a
> bitfield, but decided it is over-engineering, so kept the enum.
> 

But over-engineering is so much more fun :D

Reviewed-by: Andrew Davis <afd@ti.com>

> [2] https://github.com/beagleboard/linux/commits/v6.1.83-ti-rt-r40
> 
> V2: https://lore.kernel.org/all/20250813204106.580141-4-nm@ti.com/
> 
>   drivers/gpu/drm/bridge/ite-it66121.c | 14 +++++++++-----
>   1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
> index 5ac9631bcd9a..a108d287722d 100644
> --- a/drivers/gpu/drm/bridge/ite-it66121.c
> +++ b/drivers/gpu/drm/bridge/ite-it66121.c
> @@ -287,6 +287,7 @@
>   enum chip_id {
>   	ID_IT6610,
>   	ID_IT66121,
> +	ID_IT66122,
>   };
>   
>   struct it66121_chip_info {
> @@ -402,7 +403,7 @@ static int it66121_configure_afe(struct it66121_ctx *ctx,
>   		if (ret)
>   			return ret;
>   
> -		if (ctx->id == ID_IT66121) {
> +		if (ctx->id == ID_IT66121 || ctx->id == ID_IT66122) {
>   			ret = regmap_write_bits(ctx->regmap, IT66121_AFE_IP_REG,
>   						IT66121_AFE_IP_EC1, 0);
>   			if (ret)
> @@ -428,7 +429,7 @@ static int it66121_configure_afe(struct it66121_ctx *ctx,
>   		if (ret)
>   			return ret;
>   
> -		if (ctx->id == ID_IT66121) {
> +		if (ctx->id == ID_IT66121 || ctx->id == ID_IT66122) {
>   			ret = regmap_write_bits(ctx->regmap, IT66121_AFE_IP_REG,
>   						IT66121_AFE_IP_EC1,
>   						IT66121_AFE_IP_EC1);
> @@ -599,7 +600,7 @@ static int it66121_bridge_attach(struct drm_bridge *bridge,
>   	if (ret)
>   		return ret;
>   
> -	if (ctx->id == ID_IT66121) {
> +	if (ctx->id == ID_IT66121 || ctx->id == ID_IT66122) {
>   		ret = regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
>   					IT66121_CLK_BANK_PWROFF_RCLK, 0);
>   		if (ret)
> @@ -802,7 +803,7 @@ void it66121_bridge_mode_set(struct drm_bridge *bridge,
>   	if (regmap_write(ctx->regmap, IT66121_HDMI_MODE_REG, IT66121_HDMI_MODE_HDMI))
>   		goto unlock;
>   
> -	if (ctx->id == ID_IT66121 &&
> +	if ((ctx->id == ID_IT66121 || ctx->id == ID_IT66122) &&
>   	    regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
>   			      IT66121_CLK_BANK_PWROFF_TXCLK,
>   			      IT66121_CLK_BANK_PWROFF_TXCLK)) {
> @@ -815,7 +816,7 @@ void it66121_bridge_mode_set(struct drm_bridge *bridge,
>   	if (it66121_configure_afe(ctx, adjusted_mode))
>   		goto unlock;
>   
> -	if (ctx->id == ID_IT66121 &&
> +	if ((ctx->id == ID_IT66121 || ctx->id == ID_IT66122) &&
>   	    regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
>   			      IT66121_CLK_BANK_PWROFF_TXCLK, 0)) {
>   		goto unlock;
> @@ -1614,12 +1615,14 @@ static void it66121_remove(struct i2c_client *client)
>   }
>   
>   static const struct it66121_chip_info it66xx_chip_info[] = {
> +	{.id = ID_IT66122, .vid = 0x4954, .pid = 0x0622 },
>   	{.id = ID_IT66121, .vid = 0x4954, .pid = 0x0612 },
>   	{.id = ID_IT6610, .vid = 0xca00, .pid = 0x0611 },
>   	{ }
>   };
>   
>   static const struct of_device_id it66121_dt_match[] = {
> +	{ .compatible = "ite,it66122", &it66xx_chip_info },
>   	{ .compatible = "ite,it66121", &it66xx_chip_info },
>   	{ .compatible = "ite,it6610", &it66xx_chip_info },
>   	{ }
> @@ -1627,6 +1630,7 @@ static const struct of_device_id it66121_dt_match[] = {
>   MODULE_DEVICE_TABLE(of, it66121_dt_match);
>   
>   static const struct i2c_device_id it66121_id[] = {
> +	{ "it66122", (kernel_ulong_t)&it66xx_chip_info },
>   	{ "it66121", (kernel_ulong_t)&it66xx_chip_info },
>   	{ "it6610", (kernel_ulong_t)&it66xx_chip_info },
>   	{ }