[PATCH v6 0/3] drm/bridge: ti-sn65dsi83: Add reverse lvds lanes support

[PATCH v6 0/3] drm/bridge: ti-sn65dsi83: Add reverse lvds lanes support

[Wojciech Dubowik]

From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

Add support for reversed lvds output lanes. With an optional
data-lanes property one can support default layout <1 2 3 4>
or reversed layout <4 3 2 1>. The property is optional and when
not set it keeps the default output layout.

Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
---
Changes iv v6:
- Fix wrong size in memcmp reported by shashiko-reviews
- Add missing Reviewed-by Krzysztof in dt-bindings
Changes in v5:
- Add an extra patch to simplify error handling in lvds DT parsing
  suggested by Luca
- Fix formatting and description in dt-bindings - Krzysztof
- Make naming consistent for lane mappings constants - Luca
- Simplify parsing of data-lanes - Luca
Changes in v4:
- Fix data-lanes bindings to be under endpoint subnode and not in
  the node itself, discovered by shashiko-reviews
Changes in v3:
- Add optional data-lanes bindings for output nodes
Changes in v2:
- Parse existing data-lanes property instead of ading new DT
  bindings
---
Wojciech Dubowik (3):
  drm/bridge: ti-sn65dsi83: Simplify error condition logic
  dt-bindings: display: sn65dsi83: Add output data-lanes property
  drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support

 .../bindings/display/bridge/ti,sn65dsi83.yaml | 44 ++++++++++++
 drivers/gpu/drm/bridge/ti-sn65dsi83.c         | 72 +++++++++++--------
 2 files changed, 87 insertions(+), 29 deletions(-)

-- 
2.47.3

[PATCH v6 1/3] drm/bridge: ti-sn65dsi83: Simplify error condition logic

[Wojciech Dubowik]

From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

Simplify error condition logic in lvds device tree property parsing. It
makes it easier to add extra properties without handling complex goto
entries.

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Tested-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 43 ++++++++-------------------
 1 file changed, 13 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 42b451432bbb..f8a786953526 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -825,48 +825,35 @@ static int sn65dsi83_select_lvds_vod_swing(struct device *dev,
 static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
 {
 	struct device *dev = ctx->dev;
-	struct device_node *endpoint;
-	int endpoint_reg;
+	int endpoint_reg = (channel == CHANNEL_A) ? 2 : 3;
+	struct device_node *endpoint __free(device_node) =
+		of_graph_get_endpoint_by_regs(dev->of_node, endpoint_reg, -1);
 	/* Set so the property can be freely selected if not defined */
 	u32 lvds_vod_swing_data[2] = { 0, 1000000 };
 	u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
 	/* Set default near end terminataion to 200 Ohm */
 	u32 lvds_term = 200;
 	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 == 100)
 		ctx->lvds_term_conf[channel] = OHM_100;
 	else if (lvds_term == 200)
 		ctx->lvds_term_conf[channel] = OHM_200;
-	else {
-		ret = -EINVAL;
-		goto exit;
-	}
+	else
+		return -EINVAL;
 
 	ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
 					lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));
-	if (ret_data != 0 && ret_data != -EINVAL) {
-		ret = ret_data;
-		goto exit;
-	}
+	if (ret_data != 0 && ret_data != -EINVAL)
+		return ret_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 (ret_clock != 0 && ret_clock != -EINVAL) {
-		ret = ret_clock;
-		goto exit;
-	}
+	if (ret_clock != 0 && ret_clock != -EINVAL)
+		return ret_clock;
 
 	/* Use default value if both properties are NOT defined. */
 	if (ret_data == -EINVAL && ret_clock == -EINVAL)
@@ -876,17 +863,13 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
 	if (!ret_data || !ret_clock) {
 		lvds_vod_swing_conf = sn65dsi83_select_lvds_vod_swing(dev, lvds_vod_swing_data,
 						lvds_vod_swing_clk, ctx->lvds_term_conf[channel]);
-		if (lvds_vod_swing_conf < 0) {
-			ret = lvds_vod_swing_conf;
-			goto exit;
-		}
+		if (lvds_vod_swing_conf < 0)
+			return lvds_vod_swing_conf;
 	}
 
 	ctx->lvds_vod_swing_conf[channel] = lvds_vod_swing_conf;
-	ret = 0;
-exit:
-	of_node_put(endpoint);
-	return ret;
+
+	return 0;
 }
 
 static int sn65dsi83_parse_dt(struct sn65dsi83 *ctx, enum sn65dsi83_model model)
-- 
2.47.3

[PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property

[Wojciech Dubowik]

From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

Add an optional output lvds data lanes property with two allowed values.
The array <1 2 3 4> for standard layout and <4 3 2 1> for reversed lvds
output lanes. The latter informs the driver that reverse lvds config
option has to be set in config register for the respective output channel.

Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
---
 .../bindings/display/bridge/ti,sn65dsi83.yaml | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
index e69b6343a8eb..4000bf0b1370 100644
--- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
@@ -86,10 +86,54 @@ properties:
         description: Video port for LVDS Channel-A output (panel or bridge).
         $ref: '#/$defs/lvds-port'
 
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+            properties:
+              data-lanes:
+                $ref: /schemas/types.yaml#/definitions/uint32-array
+                description:
+                  Array of physical LVDS data lane indexes
+                oneOf:
+                  - items:
+                      - const: 1
+                      - const: 2
+                      - const: 3
+                      - const: 4
+                  - items:
+                      - const: 4
+                      - const: 3
+                      - const: 2
+                      - const: 1
+
       port@3:
         description: Video port for LVDS Channel-B output (panel or bridge).
         $ref: '#/$defs/lvds-port'
 
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+
+            properties:
+              data-lanes:
+                $ref: /schemas/types.yaml#/definitions/uint32-array
+                description:
+                  Array of physical LVDS data lane indexes
+                oneOf:
+                  - items:
+                      - const: 1
+                      - const: 2
+                      - const: 3
+                      - const: 4
+                  - items:
+                      - const: 4
+                      - const: 3
+                      - const: 2
+                      - const: 1
+
     required:
       - port@0
       - port@2
-- 
2.47.3

[PATCH v6 3/3] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support

[Wojciech Dubowik]

From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

The chip supports output lvds lanes in two orders, the default <1 2 3 4>
and <4 3 2 1>. Add parsing of an optional output lvds data-lanes property
so we can inform chip that the lanes have been reversed.

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 31 +++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index f8a786953526..182e58a0ed41 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -148,6 +148,18 @@ enum sn65dsi83_lvds_term {
 	OHM_200
 };
 
+enum {
+	LANE_MAPPING_NORMAL,
+	LANE_MAPPING_REVERSE,
+};
+
+#define DATA_LANES_COUNT	4
+
+static const u32 supported_data_lane_mapping[][DATA_LANES_COUNT] = {
+	[LANE_MAPPING_NORMAL] = { 1, 2, 3, 4 },
+	[LANE_MAPPING_REVERSE] = { 4, 3, 2, 1},
+};
+
 enum sn65dsi83_model {
 	MODEL_SN65DSI83,
 	MODEL_SN65DSI84,
@@ -163,6 +175,7 @@ struct sn65dsi83 {
 	struct regulator		*vcc;
 	bool				lvds_dual_link;
 	bool				lvds_dual_link_even_odd_swap;
+	bool				lvds_reverse_lanes_conf[2];
 	int				lvds_vod_swing_conf[2];
 	int				lvds_term_conf[2];
 	int				irq;
@@ -644,6 +657,10 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
 	regmap_write(ctx->regmap, REG_LVDS_LANE,
 		     (ctx->lvds_dual_link_even_odd_swap ?
 		      REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
+		     (ctx->lvds_reverse_lanes_conf[CHANNEL_A] ?
+		      REG_LVDS_LANE_CHA_REVERSE_LVDS : 0) |
+		     (ctx->lvds_reverse_lanes_conf[CHANNEL_B] ?
+		      REG_LVDS_LANE_CHB_REVERSE_LVDS : 0) |
 		     (ctx->lvds_term_conf[CHANNEL_A] ?
 			  REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
 		     (ctx->lvds_term_conf[CHANNEL_B] ?
@@ -833,6 +850,7 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
 	u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
 	/* Set default near end terminataion to 200 Ohm */
 	u32 lvds_term = 200;
+	u32 data_lanes[DATA_LANES_COUNT];
 	int lvds_vod_swing_conf;
 	int ret_data;
 	int ret_clock;
@@ -845,6 +863,19 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
 	else
 		return -EINVAL;
 
+	ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
+			ARRAY_SIZE(data_lanes));
+	if (!ret_data) {
+		if (memcmp(data_lanes,
+				supported_data_lane_mapping[LANE_MAPPING_REVERSE],
+				sizeof(data_lanes)) == 0)
+			ctx->lvds_reverse_lanes_conf[channel] = true;
+		else if (memcmp(data_lanes,
+			   supported_data_lane_mapping[LANE_MAPPING_NORMAL],
+			   sizeof(data_lanes)) != 0)
+			return dev_err_probe(dev, -EINVAL, "invalid data lanes mapping\n");
+	}
+
 	ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
 					lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));
 	if (ret_data != 0 && ret_data != -EINVAL)
-- 
2.47.3

Re: [PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Redefining `endpoint` in `port@2` and `port@3` with `unevaluatedProperties: false` unconditionally rejects valid vendor-specific properties (`ti,lvds-*`), breaking schema validation.
--

--- Patch [2]: [PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property ---
commit c8014187b83b236fe065488764ddd649223ae575
Author: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
dt-bindings: display: sn65dsi83: Add output data-lanes property

Adds an optional output lvds data lanes property with two allowed values
for standard and reversed layouts, informing the driver if the reverse
lvds config option needs to be set.

> diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
> index e69b6343a8ebb..4000bf0b13709 100644
> --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
> @@ -86,10 +86,54 @@ properties:
>          description: Video port for LVDS Channel-A output (panel or bridge).
>          $ref: '#/$defs/lvds-port'
>  
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false

[Severity: Medium]
Does this local redefinition of endpoint with unevaluatedProperties: false 
unconditionally reject valid vendor-specific properties (like ti,lvds-*) 
and break schema validation? 

In JSON Schema, unevaluatedProperties only considers properties evaluated 
within its own local evaluation path, so it won't see properties evaluated 
by the parallel $ref: '#/$defs/lvds-port'.

Could data-lanes be added directly to the 
#/$defs/lvds-port/properties/endpoint definition instead?

[ ... ]
>        port@3:
>          description: Video port for LVDS Channel-B output (panel or bridge).
>          $ref: '#/$defs/lvds-port'
>  
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false

[Severity: Medium]
Will this local redefinition also mask properties evaluated by 
$defs/lvds-port and cause dt_binding_check to falsely report errors for 
compliant device trees?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260721071253.1098652-1-wojciech.dubowik@mt.com?part=2

Re: [PATCH v6 3/3] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing error check causes genuinely malformed 'data-lanes' property to be silently ignored.
--

--- Patch [3]: [PATCH v6 3/3] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support ---
commit b4313ac661e9afa3be192ed6d9fd4791e5f7c33a
Author: Wojciech Dubowik <Wojciech.Dubowik@mt.com>

drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support

This commit adds support for parsing an optional "data-lanes" property to
configure the ti-sn65dsi83 chip when LVDS output lanes have been reversed, 
allowing it to program the corresponding hardware registers accordingly.

> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index 1869ebe13366c..e1b6e22bed359 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c

[ ... ]

> @@ -845,6 +863,19 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
>  	else
>  		return -EINVAL;
>  
> +	ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
> +			ARRAY_SIZE(data_lanes));
> +	if (!ret_data) {
> +		if (memcmp(data_lanes,
> +				supported_data_lane_mapping[LANE_MAPPING_REVERSE],
> +				sizeof(data_lanes)) == 0)
> +			ctx->lvds_reverse_lanes_conf[channel] = true;
> +		else if (memcmp(data_lanes,
> +			   supported_data_lane_mapping[LANE_MAPPING_NORMAL],
> +			   sizeof(data_lanes)) != 0)
> +			return dev_err_probe(dev, -EINVAL, "invalid data lanes mapping\n");
> +	}
> +
>  	ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
>  					lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));

[Severity: Medium]
If the "data-lanes" property exists but is malformed (for example, containing an
incorrect number of elements and returning -EOVERFLOW), ret_data will be
non-zero and the error is ignored. The ret_data variable is then immediately
overwritten by the next property read.

Should we check for error codes other than -EINVAL (which indicates the optional
property is absent) and return an error, rather than silently ignoring malformed
device tree properties?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260721071253.1098652-1-wojciech.dubowik@mt.com?part=3

Re: [PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property

[Krzysztof Kozlowski]

On 21/07/2026 09:12, Wojciech Dubowik wrote:
> From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
> 
> Add an optional output lvds data lanes property with two allowed values.
> The array <1 2 3 4> for standard layout and <4 3 2 1> for reversed lvds
> output lanes. The latter informs the driver that reverse lvds config
> option has to be set in config register for the respective output channel.
> 
> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>

You are not allowed to invent tag contents. This is not what you received.

<form letter>
This is a friendly reminder during the review process.

It looks like you received a tag and forgot to add it.

If you do not know the process, here is a short explanation:
Please add Acked-by/Reviewed-by/Tested-by tags when posting new versions
of patchset, under or above your Signed-off-by tag, unless patch changed
significantly (e.g. new properties added to the DT bindings). Tag is
"received", when provided in a message replied to you on the mailing
list. Tools like b4 can help here. However, there's no need to repost
patches *only* to add the tags. The upstream maintainer will do that for
tags received on the version they apply.

Please read:
https://elixir.bootlin.com/linux/v6.12-rc3/source/Documentation/process/submitting-patches.rst#L577

If a tag was not added on purpose, please state in the patch changelog
or cover letter why and what changed.
</form letter>


Best regards,
Krzysztof

Re: [PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property

[Rob Herring]

On Tue, Jul 21, 2026 at 07:20:21AM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Redefining `endpoint` in `port@2` and `port@3` with `unevaluatedProperties: false` unconditionally rejects valid vendor-specific properties (`ti,lvds-*`), breaking schema validation.
> --
> 
> --- Patch [2]: [PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property ---
> commit c8014187b83b236fe065488764ddd649223ae575
> Author: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
> dt-bindings: display: sn65dsi83: Add output data-lanes property
> 
> Adds an optional output lvds data lanes property with two allowed values
> for standard and reversed layouts, informing the driver if the reverse
> lvds config option needs to be set.
> 
> > diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
> > index e69b6343a8ebb..4000bf0b13709 100644
> > --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
> > +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi83.yaml
> > @@ -86,10 +86,54 @@ properties:
> >          description: Video port for LVDS Channel-A output (panel or bridge).
> >          $ref: '#/$defs/lvds-port'
> >  
> > +        properties:
> > +          endpoint:
> > +            $ref: /schemas/media/video-interfaces.yaml#
> > +            unevaluatedProperties: false
> 
> [Severity: Medium]
> Does this local redefinition of endpoint with unevaluatedProperties: false 
> unconditionally reject valid vendor-specific properties (like ti,lvds-*) 
> and break schema validation? 
> 
> In JSON Schema, unevaluatedProperties only considers properties evaluated 
> within its own local evaluation path, so it won't see properties evaluated 
> by the parallel $ref: '#/$defs/lvds-port'.

sashiko is right here.

Rob

Re: [PATCH v6 2/3] dt-bindings: display: sn65dsi83: Add output data-lanes property

[Rob Herring]

On Tue, Jul 21, 2026 at 09:27:46AM +0200, Krzysztof Kozlowski wrote:
> On 21/07/2026 09:12, Wojciech Dubowik wrote:
> > From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
> > 
> > Add an optional output lvds data lanes property with two allowed values.
> > The array <1 2 3 4> for standard layout and <4 3 2 1> for reversed lvds
> > output lanes. The latter informs the driver that reverse lvds config
> > option has to be set in config register for the respective output channel.
> > 
> > Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
> 
> You are not allowed to invent tag contents. This is not what you received.

You may want to reconsider any tag other than nak. This is fundamentally 
flawed which sashiko has pointed out since v4 and has been ignored.

Rob