diff mbox series

[v2,2/3] drm/bridge: ti-sn65dsi83: Add ti,lvds-vod-swing optional properties

Message ID 20241203085822.2475138-3-andrej.picej@norik.com (mailing list archive)
State New
Headers show
Series SN65DSI83/4 lvds_vod_swing properties | expand

Commit Message

Andrej Picej Dec. 3, 2024, 8:58 a.m. UTC
Add a optional properties to change LVDS output voltage. This should not
be static as this depends mainly on the connected display voltage
requirement. We have three properties:
- "ti,lvds-termination-ohms", which sets near end termination,
- "ti,lvds-vod-swing-data-microvolt" and
- "ti,lvds-vod-swing-clock-microvolt" which both set LVDS differential
output voltage for data and clock lanes. They are defined as an array
with min and max values. The appropriate bitfiled will be set if
selected constraints can be met.

If "ti,lvds-termination-ohms" is not defined the default of 200 Ohm near
end termination will be used. Selecting only one:
"ti,lvds-vod-swing-data-microvolt" or
"ti,lvds-vod-swing-clock-microvolt" can be done, but the output voltage
constraint for only data/clock lanes will be met. Setting both is
recommended.

Signed-off-by: Andrej Picej <andrej.picej@norik.com>
---
Changes in v2:
- use datasheet tables to get the proper configuration
- since major change was done change the authorship to myself
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 144 +++++++++++++++++++++++++-
 1 file changed, 141 insertions(+), 3 deletions(-)

Comments

Andrej Picej Dec. 3, 2024, 9:40 a.m. UTC | #1
Hi all,

On 3. 12. 24 09:58, Andrej Picej wrote:
> Add a optional properties to change LVDS output voltage. This should not
> be static as this depends mainly on the connected display voltage
> requirement. We have three properties:
> - "ti,lvds-termination-ohms", which sets near end termination,
> - "ti,lvds-vod-swing-data-microvolt" and
> - "ti,lvds-vod-swing-clock-microvolt" which both set LVDS differential
> output voltage for data and clock lanes. They are defined as an array
> with min and max values. The appropriate bitfiled will be set if
> selected constraints can be met.
> 
> If "ti,lvds-termination-ohms" is not defined the default of 200 Ohm near
> end termination will be used. Selecting only one:
> "ti,lvds-vod-swing-data-microvolt" or
> "ti,lvds-vod-swing-clock-microvolt" can be done, but the output voltage
> constraint for only data/clock lanes will be met. Setting both is
> recommended.
> 
> Signed-off-by: Andrej Picej <andrej.picej@norik.com>
> ---
> Changes in v2:
> - use datasheet tables to get the proper configuration
> - since major change was done change the authorship to myself
> ---
>   drivers/gpu/drm/bridge/ti-sn65dsi83.c | 144 +++++++++++++++++++++++++-
>   1 file changed, 141 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index 57a7ed13f996..44445d7ad52a 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -132,6 +132,16 @@
>   #define  REG_IRQ_STAT_CHA_SOT_BIT_ERR		BIT(2)
>   #define  REG_IRQ_STAT_CHA_PLL_UNLOCK		BIT(0)
>   
> +enum sn65dsi83_channel {
> +	CHANNEL_A,
> +	CHANNEL_B
> +};
> +
> +enum sn65dsi83_lvds_term {
> +	OHM_100,
> +	OHM_200
> +};
> +
>   enum sn65dsi83_model {
>   	MODEL_SN65DSI83,
>   	MODEL_SN65DSI84,
> @@ -147,6 +157,10 @@ struct sn65dsi83 {
>   	struct regulator		*vcc;
>   	bool				lvds_dual_link;
>   	bool				lvds_dual_link_even_odd_swap;
> +	int				lvdsA_vod_swing_conf;
> +	int				lvdsB_vod_swing_conf;
> +	int				lvdsA_term_conf;
> +	int				lvdsB_term_conf;
>   };
>   
>   static const struct regmap_range sn65dsi83_readable_ranges[] = {
> @@ -237,6 +251,36 @@ static const struct regmap_config sn65dsi83_regmap_config = {
>   	.max_register = REG_IRQ_STAT,
>   };
>   
> +static const int lvds_vod_swing_data_table[2][4][2] = {
> +	{	/* 100 Ohm */
> +		{ 180000, 313000 },
> +		{ 215000, 372000 },
> +		{ 250000, 430000 },
> +		{ 290000, 488000 },
> +	},
> +	{	/* 200 Ohm */
> +		{ 150000, 261000 },
> +		{ 200000, 346000 },
> +		{ 250000, 428000 },
> +		{ 300000, 511000 },
> +	},
> +};
> +
> +static const int lvds_vod_swing_clock_table[2][4][2] = {
> +	{	/* 100 Ohm */
> +		{ 140000, 244000 },
> +		{ 168000, 290000 },
> +		{ 195000, 335000 },
> +		{ 226000, 381000 },
> +	},
> +	{	/* 200 Ohm */
> +		{ 117000, 204000 },
> +		{ 156000, 270000 },
> +		{ 195000, 334000 },
> +		{ 234000, 399000 },
> +	},
> +};
> +
>   static struct sn65dsi83 *bridge_to_sn65dsi83(struct drm_bridge *bridge)
>   {
>   	return container_of(bridge, struct sn65dsi83, bridge);
> @@ -435,12 +479,16 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
>   		val |= REG_LVDS_FMT_LVDS_LINK_CFG;
>   
>   	regmap_write(ctx->regmap, REG_LVDS_FMT, val);
> -	regmap_write(ctx->regmap, REG_LVDS_VCOM, 0x05);
> +	regmap_write(ctx->regmap, REG_LVDS_VCOM,
> +			REG_LVDS_VCOM_CHA_LVDS_VOD_SWING(ctx->lvdsA_vod_swing_conf) |
> +			REG_LVDS_VCOM_CHB_LVDS_VOD_SWING(ctx->lvdsB_vod_swing_conf));
>   	regmap_write(ctx->regmap, REG_LVDS_LANE,
>   		     (ctx->lvds_dual_link_even_odd_swap ?
>   		      REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
> -		     REG_LVDS_LANE_CHA_LVDS_TERM |
> -		     REG_LVDS_LANE_CHB_LVDS_TERM);
> +		     (ctx->lvdsA_term_conf ?
> +			  REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
> +		     (ctx->lvdsB_term_conf ?
> +			  REG_LVDS_LANE_CHB_LVDS_TERM : 0));
>   	regmap_write(ctx->regmap, REG_LVDS_CM, 0x00);
>   
>   	le16val = cpu_to_le16(mode->hdisplay);
> @@ -576,10 +624,96 @@ static const struct drm_bridge_funcs sn65dsi83_funcs = {
>   	.atomic_get_input_bus_fmts = sn65dsi83_atomic_get_input_bus_fmts,
>   };
>   
> +static int sn65dsi83_select_lvds_vod_swing(struct device *dev,
> +	u32 lvds_vod_swing_data[2], u32 lvds_vod_swing_clk[2], u8 lvds_term)
> +{
> +	int i;
> +
> +	for (i = 0; i <= 3; i++) {
> +		if (lvds_vod_swing_data_table[lvds_term][i][0] >= lvds_vod_swing_data[0] &&
> +		lvds_vod_swing_data_table[lvds_term][i][1] <= lvds_vod_swing_data[1] &&
> +		lvds_vod_swing_clock_table[lvds_term][i][0] >= lvds_vod_swing_clk[0] &&
> +		lvds_vod_swing_clock_table[lvds_term][i][1] <= lvds_vod_swing_clk[1])
> +			return i;
> +	}
> +
> +	dev_err(dev, "failed to find appropriate LVDS_VOD_SWING configuration\n");
> +	return -EINVAL;
> +}
> +
> +static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
> +{
> +	struct device *dev = ctx->dev;
> +	struct device_node *endpoint;
> +	/* Set so the property can be freely selected if not defined */
> +	u32 lvds_vod_swing_data[2] = { 0, 1000 };
> +	u32 lvds_vod_swing_clk[2] = { 0, 1000 };

I moved the code from milivolts to standard kernel voltage units 
microvolts quite recently and accidentaly forgot to apply these changes 
from my src tree. These should be:
+	u32 lvds_vod_swing_data[2] = { 0, 1000000 };
+	u32 lvds_vod_swing_clk[2] = { 0, 1000000 };

The code was tested with it though.

Will send a v3 ASAP. Sorry for this.

BR,
Andrej

> +	u32 lvds_term = 200;
> +	u8 lvds_term_conf;
> +	int endpoint_reg;
> +	int lvds_vod_swing_conf;
> +	int ret = 0;
> +	int ret_data;
> +	int ret_clock;
> +
> +	if (channel == CHANNEL_A)
> +		endpoint_reg = 2;
> +	else
> +		endpoint_reg = 3;
> +
> +	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, endpoint_reg, -1);
> +	of_property_read_u32(endpoint, "ti,lvds-termination-ohms", &lvds_term);
> +
> +	if (lvds_term == 200)
> +		lvds_term_conf = OHM_200;
> +	else
> +		lvds_term_conf = OHM_100;
> +
> +	if (channel == CHANNEL_A)
> +		ctx->lvdsA_term_conf = lvds_term_conf;
> +	else
> +		ctx->lvdsB_term_conf = lvds_term_conf;
> +
> +	ret_data = of_property_read_u32_array(endpoint,
> +			"ti,lvds-vod-swing-data-microvolt", lvds_vod_swing_data,
> +			ARRAY_SIZE(lvds_vod_swing_data));
> +	ret_clock = of_property_read_u32_array(endpoint,
> +			"ti,lvds-vod-swing-clock-microvolt", lvds_vod_swing_clk,
> +			ARRAY_SIZE(lvds_vod_swing_clk));
> +	/* If any of the two properties is defined. */
> +	if (!ret_data || !ret_clock) {
> +		lvds_vod_swing_conf = sn65dsi83_select_lvds_vod_swing(dev,
> +			lvds_vod_swing_data, lvds_vod_swing_clk,
> +			lvds_term_conf);
> +		if (lvds_vod_swing_conf < 0) {
> +			ret = lvds_vod_swing_conf;
> +			goto exit;
> +		}
> +		if (channel == CHANNEL_A)
> +			ctx->lvdsA_vod_swing_conf = lvds_vod_swing_conf;
> +		else
> +			ctx->lvdsB_vod_swing_conf = lvds_vod_swing_conf;
> +	}
> +	ret = 0;
> +exit:
> +	of_node_put(endpoint);
> +	return ret;
> +}
> +
>   static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
>   {
>   	struct drm_bridge *panel_bridge;
>   	struct device *dev = ctx->dev;
> +	int ret;
> +
> +	ctx->lvdsA_vod_swing_conf = 0x1;
> +	ctx->lvdsB_vod_swing_conf = 0x1;
> +	ctx->lvdsA_term_conf = 0x1;
> +	ctx->lvdsB_term_conf = 0x1;
> +
> +	ret = sn65dsi83_parse_lvds_endpoint(ctx, CHANNEL_A);
> +	if (ret < 0)
> +		return ret;
>   
>   	ctx->lvds_dual_link = false;
>   	ctx->lvds_dual_link_even_odd_swap = false;
> @@ -587,6 +721,10 @@ static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
>   		struct device_node *port2, *port3;
>   		int dual_link;
>   
> +		ret = sn65dsi83_parse_lvds_endpoint(ctx, CHANNEL_B);
> +		if (ret < 0)
> +			return ret;
> +
>   		port2 = of_graph_get_port_by_id(dev->of_node, 2);
>   		port3 = of_graph_get_port_by_id(dev->of_node, 3);
>   		dual_link = drm_of_lvds_get_dual_link_pixel_order(port2, port3);
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 57a7ed13f996..44445d7ad52a 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -132,6 +132,16 @@ 
 #define  REG_IRQ_STAT_CHA_SOT_BIT_ERR		BIT(2)
 #define  REG_IRQ_STAT_CHA_PLL_UNLOCK		BIT(0)
 
+enum sn65dsi83_channel {
+	CHANNEL_A,
+	CHANNEL_B
+};
+
+enum sn65dsi83_lvds_term {
+	OHM_100,
+	OHM_200
+};
+
 enum sn65dsi83_model {
 	MODEL_SN65DSI83,
 	MODEL_SN65DSI84,
@@ -147,6 +157,10 @@  struct sn65dsi83 {
 	struct regulator		*vcc;
 	bool				lvds_dual_link;
 	bool				lvds_dual_link_even_odd_swap;
+	int				lvdsA_vod_swing_conf;
+	int				lvdsB_vod_swing_conf;
+	int				lvdsA_term_conf;
+	int				lvdsB_term_conf;
 };
 
 static const struct regmap_range sn65dsi83_readable_ranges[] = {
@@ -237,6 +251,36 @@  static const struct regmap_config sn65dsi83_regmap_config = {
 	.max_register = REG_IRQ_STAT,
 };
 
+static const int lvds_vod_swing_data_table[2][4][2] = {
+	{	/* 100 Ohm */
+		{ 180000, 313000 },
+		{ 215000, 372000 },
+		{ 250000, 430000 },
+		{ 290000, 488000 },
+	},
+	{	/* 200 Ohm */
+		{ 150000, 261000 },
+		{ 200000, 346000 },
+		{ 250000, 428000 },
+		{ 300000, 511000 },
+	},
+};
+
+static const int lvds_vod_swing_clock_table[2][4][2] = {
+	{	/* 100 Ohm */
+		{ 140000, 244000 },
+		{ 168000, 290000 },
+		{ 195000, 335000 },
+		{ 226000, 381000 },
+	},
+	{	/* 200 Ohm */
+		{ 117000, 204000 },
+		{ 156000, 270000 },
+		{ 195000, 334000 },
+		{ 234000, 399000 },
+	},
+};
+
 static struct sn65dsi83 *bridge_to_sn65dsi83(struct drm_bridge *bridge)
 {
 	return container_of(bridge, struct sn65dsi83, bridge);
@@ -435,12 +479,16 @@  static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
 		val |= REG_LVDS_FMT_LVDS_LINK_CFG;
 
 	regmap_write(ctx->regmap, REG_LVDS_FMT, val);
-	regmap_write(ctx->regmap, REG_LVDS_VCOM, 0x05);
+	regmap_write(ctx->regmap, REG_LVDS_VCOM,
+			REG_LVDS_VCOM_CHA_LVDS_VOD_SWING(ctx->lvdsA_vod_swing_conf) |
+			REG_LVDS_VCOM_CHB_LVDS_VOD_SWING(ctx->lvdsB_vod_swing_conf));
 	regmap_write(ctx->regmap, REG_LVDS_LANE,
 		     (ctx->lvds_dual_link_even_odd_swap ?
 		      REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
-		     REG_LVDS_LANE_CHA_LVDS_TERM |
-		     REG_LVDS_LANE_CHB_LVDS_TERM);
+		     (ctx->lvdsA_term_conf ?
+			  REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
+		     (ctx->lvdsB_term_conf ?
+			  REG_LVDS_LANE_CHB_LVDS_TERM : 0));
 	regmap_write(ctx->regmap, REG_LVDS_CM, 0x00);
 
 	le16val = cpu_to_le16(mode->hdisplay);
@@ -576,10 +624,96 @@  static const struct drm_bridge_funcs sn65dsi83_funcs = {
 	.atomic_get_input_bus_fmts = sn65dsi83_atomic_get_input_bus_fmts,
 };
 
+static int sn65dsi83_select_lvds_vod_swing(struct device *dev,
+	u32 lvds_vod_swing_data[2], u32 lvds_vod_swing_clk[2], u8 lvds_term)
+{
+	int i;
+
+	for (i = 0; i <= 3; i++) {
+		if (lvds_vod_swing_data_table[lvds_term][i][0] >= lvds_vod_swing_data[0] &&
+		lvds_vod_swing_data_table[lvds_term][i][1] <= lvds_vod_swing_data[1] &&
+		lvds_vod_swing_clock_table[lvds_term][i][0] >= lvds_vod_swing_clk[0] &&
+		lvds_vod_swing_clock_table[lvds_term][i][1] <= lvds_vod_swing_clk[1])
+			return i;
+	}
+
+	dev_err(dev, "failed to find appropriate LVDS_VOD_SWING configuration\n");
+	return -EINVAL;
+}
+
+static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
+{
+	struct device *dev = ctx->dev;
+	struct device_node *endpoint;
+	/* Set so the property can be freely selected if not defined */
+	u32 lvds_vod_swing_data[2] = { 0, 1000 };
+	u32 lvds_vod_swing_clk[2] = { 0, 1000 };
+	u32 lvds_term = 200;
+	u8 lvds_term_conf;
+	int endpoint_reg;
+	int lvds_vod_swing_conf;
+	int ret = 0;
+	int ret_data;
+	int ret_clock;
+
+	if (channel == CHANNEL_A)
+		endpoint_reg = 2;
+	else
+		endpoint_reg = 3;
+
+	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, endpoint_reg, -1);
+	of_property_read_u32(endpoint, "ti,lvds-termination-ohms", &lvds_term);
+
+	if (lvds_term == 200)
+		lvds_term_conf = OHM_200;
+	else
+		lvds_term_conf = OHM_100;
+
+	if (channel == CHANNEL_A)
+		ctx->lvdsA_term_conf = lvds_term_conf;
+	else
+		ctx->lvdsB_term_conf = lvds_term_conf;
+
+	ret_data = of_property_read_u32_array(endpoint,
+			"ti,lvds-vod-swing-data-microvolt", lvds_vod_swing_data,
+			ARRAY_SIZE(lvds_vod_swing_data));
+	ret_clock = of_property_read_u32_array(endpoint,
+			"ti,lvds-vod-swing-clock-microvolt", lvds_vod_swing_clk,
+			ARRAY_SIZE(lvds_vod_swing_clk));
+	/* If any of the two properties is defined. */
+	if (!ret_data || !ret_clock) {
+		lvds_vod_swing_conf = sn65dsi83_select_lvds_vod_swing(dev,
+			lvds_vod_swing_data, lvds_vod_swing_clk,
+			lvds_term_conf);
+		if (lvds_vod_swing_conf < 0) {
+			ret = lvds_vod_swing_conf;
+			goto exit;
+		}
+		if (channel == CHANNEL_A)
+			ctx->lvdsA_vod_swing_conf = lvds_vod_swing_conf;
+		else
+			ctx->lvdsB_vod_swing_conf = lvds_vod_swing_conf;
+	}
+	ret = 0;
+exit:
+	of_node_put(endpoint);
+	return ret;
+}
+
 static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
 {
 	struct drm_bridge *panel_bridge;
 	struct device *dev = ctx->dev;
+	int ret;
+
+	ctx->lvdsA_vod_swing_conf = 0x1;
+	ctx->lvdsB_vod_swing_conf = 0x1;
+	ctx->lvdsA_term_conf = 0x1;
+	ctx->lvdsB_term_conf = 0x1;
+
+	ret = sn65dsi83_parse_lvds_endpoint(ctx, CHANNEL_A);
+	if (ret < 0)
+		return ret;
 
 	ctx->lvds_dual_link = false;
 	ctx->lvds_dual_link_even_odd_swap = false;
@@ -587,6 +721,10 @@  static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
 		struct device_node *port2, *port3;
 		int dual_link;
 
+		ret = sn65dsi83_parse_lvds_endpoint(ctx, CHANNEL_B);
+		if (ret < 0)
+			return ret;
+
 		port2 = of_graph_get_port_by_id(dev->of_node, 2);
 		port3 = of_graph_get_port_by_id(dev->of_node, 3);
 		dual_link = drm_of_lvds_get_dual_link_pixel_order(port2, port3);