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Message-ID: <e3416746-ee96-449d-8a17-28efcd391c55@ti.com>
Date: Fri, 15 Aug 2025 08:52:12 -0500
From: Andrew Davis <afd@...com>
To: Nishanth Menon <nm@...com>, 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>,
<tomi.valkeinen@...asonboard.com>, <devarsht@...com>
Subject: Re: [PATCH V3 3/4] drm/bridge: it66121: Use vid/pid to detect the
type of chip
On 8/14/25 10:41 PM, Nishanth Menon wrote:
> The driver knows exactly which version of the chip is present since
> the vid/pid is used to enforce a compatibility. Given that some
> devices like IT66121 has potentially been replaced with IT66122 mid
> production for many platforms, it makes no sense to use the vid/pid as
> an enforcement for compatibility. Instead, let us detect the ID of the
> actual chip in use by matching the corresponding vid/pid.
>
> This also allows for some future compatibility to be checked only
> against a restricted set of vid/pid.
>
> While at this, fix up a bit of formatting errors reported by
> checkpatch warning, and since the ctx info just requires the id, drop
> storing the entire chip_info pointer.
>
> Signed-off-by: Nishanth Menon <nm@...com>
> ---
> Changes in V3:
> * Converted the patch to lookup ID based on vid/pid match rather than
> enforcing vid/pid match per compatible.
> * Squashed a formating fix for pre-existing checkpatch --strict warning
>
> V2: https://lore.kernel.org/all/20250813204106.580141-3-nm@ti.com/
>
> drivers/gpu/drm/bridge/ite-it66121.c | 53 ++++++++++++++--------------
> 1 file changed, 27 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
> index 9b8ed2fae2f4..5ac9631bcd9a 100644
> --- a/drivers/gpu/drm/bridge/ite-it66121.c
> +++ b/drivers/gpu/drm/bridge/ite-it66121.c
> @@ -312,7 +312,7 @@ struct it66121_ctx {
> u8 swl;
> bool auto_cts;
> } audio;
> - const struct it66121_chip_info *info;
> + enum chip_id id;
> };
>
> static const struct regmap_range_cfg it66121_regmap_banks[] = {
> @@ -402,7 +402,7 @@ static int it66121_configure_afe(struct it66121_ctx *ctx,
> if (ret)
> return ret;
>
> - if (ctx->info->id == ID_IT66121) {
> + if (ctx->id == ID_IT66121) {
> ret = regmap_write_bits(ctx->regmap, IT66121_AFE_IP_REG,
> IT66121_AFE_IP_EC1, 0);
> if (ret)
> @@ -428,7 +428,7 @@ static int it66121_configure_afe(struct it66121_ctx *ctx,
> if (ret)
> return ret;
>
> - if (ctx->info->id == ID_IT66121) {
> + if (ctx->id == ID_IT66121) {
> ret = regmap_write_bits(ctx->regmap, IT66121_AFE_IP_REG,
> IT66121_AFE_IP_EC1,
> IT66121_AFE_IP_EC1);
> @@ -449,7 +449,7 @@ static int it66121_configure_afe(struct it66121_ctx *ctx,
> if (ret)
> return ret;
>
> - if (ctx->info->id == ID_IT6610) {
> + if (ctx->id == ID_IT6610) {
> ret = regmap_write_bits(ctx->regmap, IT66121_AFE_XP_REG,
> IT6610_AFE_XP_BYPASS,
> IT6610_AFE_XP_BYPASS);
> @@ -599,7 +599,7 @@ static int it66121_bridge_attach(struct drm_bridge *bridge,
> if (ret)
> return ret;
>
> - if (ctx->info->id == ID_IT66121) {
> + if (ctx->id == ID_IT66121) {
> ret = regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
> IT66121_CLK_BANK_PWROFF_RCLK, 0);
> if (ret)
> @@ -748,7 +748,7 @@ static int it66121_bridge_check(struct drm_bridge *bridge,
> {
> struct it66121_ctx *ctx = container_of(bridge, struct it66121_ctx, bridge);
>
> - if (ctx->info->id == ID_IT6610) {
> + if (ctx->id == ID_IT6610) {
> /* The IT6610 only supports these settings */
> bridge_state->input_bus_cfg.flags |= DRM_BUS_FLAG_DE_HIGH |
> DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE;
> @@ -802,7 +802,7 @@ 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->info->id == ID_IT66121 &&
> + if (ctx->id == ID_IT66121 &&
> regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
> IT66121_CLK_BANK_PWROFF_TXCLK,
> IT66121_CLK_BANK_PWROFF_TXCLK)) {
> @@ -815,7 +815,7 @@ void it66121_bridge_mode_set(struct drm_bridge *bridge,
> if (it66121_configure_afe(ctx, adjusted_mode))
> goto unlock;
>
> - if (ctx->info->id == ID_IT66121 &&
> + if (ctx->id == ID_IT66121 &&
> regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
> IT66121_CLK_BANK_PWROFF_TXCLK, 0)) {
> goto unlock;
> @@ -1505,6 +1505,7 @@ static int it66121_probe(struct i2c_client *client)
> int ret;
> struct it66121_ctx *ctx;
> struct device *dev = &client->dev;
> + const struct it66121_chip_info *chip_info;
>
> if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> dev_err(dev, "I2C check functionality failed.\n");
> @@ -1522,7 +1523,7 @@ static int it66121_probe(struct i2c_client *client)
>
> ctx->dev = dev;
> ctx->client = client;
> - ctx->info = i2c_get_match_data(client);
> + chip_info = i2c_get_match_data(client);
>
> of_property_read_u32(ep, "bus-width", &ctx->bus_width);
> of_node_put(ep);
> @@ -1568,11 +1569,17 @@ static int it66121_probe(struct i2c_client *client)
> revision_id = FIELD_GET(IT66121_REVISION_MASK, device_ids[1]);
> device_ids[1] &= IT66121_DEVICE_ID1_MASK;
>
> - if ((vendor_ids[1] << 8 | vendor_ids[0]) != ctx->info->vid ||
> - (device_ids[1] << 8 | device_ids[0]) != ctx->info->pid) {
> - return -ENODEV;
> + for (; chip_info->vid; chip_info++) {
> + if ((vendor_ids[1] << 8 | vendor_ids[0]) == chip_info->vid &&
> + (device_ids[1] << 8 | device_ids[0]) == chip_info->pid) {
> + ctx->id = chip_info->id;
> + break;
> + }
> }
>
> + if (!chip_info->vid)
> + return -ENODEV;
> +
> ctx->bridge.of_node = dev->of_node;
> ctx->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
> ctx->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID;
> @@ -1606,28 +1613,22 @@ static void it66121_remove(struct i2c_client *client)
> mutex_destroy(&ctx->lock);
> }
>
> -static const struct it66121_chip_info it66121_chip_info = {
> - .id = ID_IT66121,
> - .vid = 0x4954,
> - .pid = 0x0612,
> -};
> -
> -static const struct it66121_chip_info it6610_chip_info = {
> - .id = ID_IT6610,
> - .vid = 0xca00,
> - .pid = 0x0611,
> +static const struct it66121_chip_info it66xx_chip_info[] = {
> + {.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,it66121", &it66121_chip_info },
> - { .compatible = "ite,it6610", &it6610_chip_info },
> + { .compatible = "ite,it66121", &it66xx_chip_info },
> + { .compatible = "ite,it6610", &it66xx_chip_info },
If you will pass in the same data to all devices, just don't pass
anything. Move the it66121_dt_match table up above probe, and just
use it, no need for fetching it from i2c_get_match_data().
That can also be done later too, so not a blocker here,
Reviewed-by: Andrew Davis <afd@...com>
> { }
> };
> MODULE_DEVICE_TABLE(of, it66121_dt_match);
>
> static const struct i2c_device_id it66121_id[] = {
> - { "it66121", (kernel_ulong_t) &it66121_chip_info },
> - { "it6610", (kernel_ulong_t) &it6610_chip_info },
> + { "it66121", (kernel_ulong_t)&it66xx_chip_info },
> + { "it6610", (kernel_ulong_t)&it66xx_chip_info },
> { }
> };
> MODULE_DEVICE_TABLE(i2c, it66121_id);
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