linux-kernel - [PATCH V3 4/4] drm/bridge: it66121: Add minimal it66122 support

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Message-ID: <20250815034105.1276548-5-nm@ti.com>
Date: Thu, 14 Aug 2025 22:41:05 -0500
From: Nishanth Menon <nm@...com>
To: Conor Dooley <conor+dt@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Rob Herring <robh@...nel.org>, David Airlie
	<airlied@...il.com>,
        Maxime Ripard <mripard@...nel.org>,
        Laurent Pinchart
	<Laurent.pinchart@...asonboard.com>,
        Neil Armstrong
	<neil.armstrong@...aro.org>
CC: <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>,
        Robert Nelson <robertcnelson@...il.com>,
        Jason Kridner <jkridner@...gleboard.org>, <afd@...com>,
        <tomi.valkeinen@...asonboard.com>, <devarsht@...com>,
        Nishanth Menon
	<nm@...com>
Subject: [PATCH V3 4/4] drm/bridge: it66121: Add minimal it66122 support

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@...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.

[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 },
 	{ }
-- 
2.47.0