[PATCH v4 0/3] Add eDP lane mapping support

[PATCH v4 0/3] Add eDP lane mapping support

[Damon Ding]

This series adds configurable eDP physical lane mapping support via
device tree data-lanes property.

Lane mapping is mainly used for below scenarios:
1. Correct PCB lane swap and differential line routing crossover
   without hardware changes;
2. Adapt mismatched lane pin definitions between SoC and eDP panel;
3. Support multiple panel hardware variants on the same board
   by configuring data-lanes in device tree only.

The series includes driver implementation and device tree binding
updates to support custom lane mapping configuration from endpoint
node, and keeps default linear lane order if no configuration is given.

Patch 1: Add endpoint data-lanes property to analogix-dp binding
Patch 2: Add validation for samsung,lane-count property as preparation
Patch 3: Implement lane mapping in analogix_dp driver

Damon Ding (3):
  dt-bindings: display: bridge: analogix-dp: Add data-lanes support for
    endpoint
  drm/bridge: analogix_dp: Add validation for samsung,lane-count
    property
  drm/bridge: analogix_dp: Add support for optional data-lanes mapping

 .../bindings/display/bridge/analogix,dp.yaml  | 19 +++--
 .../rockchip/rockchip,analogix-dp.yaml        |  1 +
 .../drm/bridge/analogix/analogix_dp_core.c    | 69 ++++++++++++++++++-
 .../drm/bridge/analogix/analogix_dp_core.h    |  4 +-
 .../gpu/drm/bridge/analogix/analogix_dp_reg.c | 15 ++--
 .../gpu/drm/bridge/analogix/analogix_dp_reg.h |  4 ++
 6 files changed, 96 insertions(+), 16 deletions(-)

---

Changes in v2:
- Add lane mapping application scenarios in commit message.
- Remove redundant deprecated property 'data-lanes' for eDP node.
- Update port@1 $ref to /schemas/graph.yaml#/$defs/port-base.

Changes in v3:
- Squash [PATCH v2 2/3] into [PATCH v2 1/3].
- Add unevaluatedProperties: false to both the port@1 and endpoint
  nodes.

Changes in v4:
- Add validation for samsung,lane-count property as preparation.

-- 
2.34.1

[PATCH v4 1/3] dt-bindings: display: bridge: analogix-dp: Add data-lanes support for endpoint

[Damon Ding]

Add data-lanes property support to the port@1 endpoint for physical
lane mapping configuration.

Lane mapping is mainly used for below scenarios:
1. Correct PCB lane swap and differential line routing crossover
   without hardware changes;
2. Adapt mismatched lane pin definitions between SoC and eDP panel;
3. Support multiple panel hardware variants on the same board
   by configuring data-lanes in device tree only.

Additionally, add data-lanes setting in Rockchip eDP DT node example
to show actual lane mapping usage.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>

---

Changes in v2:
- Add lane mapping application scenarios in commit message.
- Remove redundant deprecated property 'data-lanes' for eDP node.
- Update port@1 $ref to /schemas/graph.yaml#/$defs/port-base.

Changes in v3:
- Squash data-lanes adjustment of Rockchip eDP DT example into this
  commit.
- Add unevaluatedProperties: false to both the port@1 and endpoint
  nodes.
---
 .../bindings/display/bridge/analogix,dp.yaml  | 19 ++++++++++++++-----
 .../rockchip/rockchip,analogix-dp.yaml        |  1 +
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml b/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml
index 62f0521b0924..ecf206871cdd 100644
--- a/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml
@@ -42,13 +42,22 @@ properties:
     properties:
       port@0:
         $ref: /schemas/graph.yaml#/properties/port
-        description:
-          Input node to receive pixel data.
+        description: Input node to receive pixel data.
 
       port@1:
-        $ref: /schemas/graph.yaml#/properties/port
-        description:
-          Port node with one endpoint connected to a dp-connector node.
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
+        description: Port node with one endpoint connected to sink device node.
+        properties:
+          endpoint:
+            $ref: /schemas/media/video-interfaces.yaml#
+            unevaluatedProperties: false
+            properties:
+              data-lanes:
+                minItems: 1
+                maxItems: 4
+                items:
+                  enum: [ 0, 1, 2, 3 ]
 
     required:
       - port@0
diff --git a/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml b/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml
index d99b23b88cc5..f690ee393fdb 100644
--- a/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml
+++ b/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml
@@ -117,6 +117,7 @@ examples:
           reg = <1>;
 
           edp_out_panel: endpoint {
+            data-lanes = <0 1>;
             remote-endpoint = <&panel_in_edp>;
           };
         };
-- 
2.34.1

[PATCH v4 2/3] drm/bridge: analogix_dp: Add validation for samsung,lane-count property

[Damon Ding]

Add range check for samsung,lane-count to avoid invalid values.
Validation is only applied when the property exists to maintain
backward compatibility.

Suggested-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
---
 drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 8cf6b73bceac..699a7f380c56 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1238,6 +1238,7 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
 {
 	struct device_node *dp_node = dp->dev->of_node;
 	struct video_info *video_info = &dp->video_info;
+	int ret;
 
 	switch (dp->plat_data->dev_type) {
 	case RK3288_DP:
@@ -1260,8 +1261,16 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
 		 */
 		of_property_read_u32(dp_node, "samsung,link-rate",
 				     &video_info->max_link_rate);
-		of_property_read_u32(dp_node, "samsung,lane-count",
-				     &video_info->max_lane_count);
+		ret = of_property_read_u32(dp_node, "samsung,lane-count",
+					   &video_info->max_lane_count);
+		if (!ret) {
+			if (video_info->max_lane_count == 0 ||
+			    video_info->max_lane_count > LANE_COUNT4) {
+				dev_err(dp->dev, "samsung,lane-count = %d is out of range\n",
+					video_info->max_lane_count);
+				return -EINVAL;
+			}
+		}
 		break;
 	}
 
-- 
2.34.1

[PATCH v4 3/3] drm/bridge: analogix_dp: Add support for optional data-lanes mapping

[Damon Ding]

Parse the optional 'data-lanes' device tree property to support
custom physical lane mapping configuration.

If no valid configuration is found, fall back to the default
lane map (0, 1, 2, 3) automatically and keep the driver running.

Lane mapping is mainly used for below scenarios:
1. Correct PCB lane swap and differential line routing crossover
   without hardware changes;
2. Adapt mismatched lane pin definitions between SoC and eDP panel;
3. Support multiple panel hardware variants on the same board
   by configuring data-lanes in device tree only.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>

---

Changes in v2:
- Add lane mapping application scenarios in commit message.
---
 .../drm/bridge/analogix/analogix_dp_core.c    | 56 +++++++++++++++++++
 .../drm/bridge/analogix/analogix_dp_core.h    |  4 +-
 .../gpu/drm/bridge/analogix/analogix_dp_reg.c | 15 +++--
 .../gpu/drm/bridge/analogix/analogix_dp_reg.h |  4 ++
 4 files changed, 70 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 699a7f380c56..b2e729850391 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -1234,6 +1234,59 @@ static const struct drm_bridge_funcs analogix_dp_bridge_funcs = {
 	.detect = analogix_dp_bridge_detect,
 };
 
+static int analogix_dp_dt_parse_lanes_map(struct analogix_dp_device *dp)
+{
+	struct video_info *video_info = &dp->video_info;
+	struct device_node *endpoint;
+	u32 tmp[LANE_COUNT4];
+	u32 map[LANE_COUNT4] = {0, 1, 2, 3};
+	bool used[LANE_COUNT4] = {false};
+	int num_lanes;
+	int ret, i;
+
+	memcpy(video_info->lane_map, map, sizeof(map));
+
+	num_lanes = drm_of_get_data_lanes_count_ep(dp->dev->of_node, 1, 0, 1,
+						   video_info->max_lane_count);
+	if (num_lanes < 0)
+		return -EINVAL;
+
+	endpoint = of_graph_get_endpoint_by_regs(dp->dev->of_node, 1, -1);
+	if (!endpoint)
+		return -EINVAL;
+
+	ret = of_property_read_u32_array(endpoint, "data-lanes", tmp, num_lanes);
+	of_node_put(endpoint);
+	if (ret)
+		return -EINVAL;
+
+	for (i = 0; i < num_lanes; i++) {
+		if (tmp[i] >= LANE_COUNT4) {
+			dev_dbg(dp->dev, "data-lanes[%d] = %u is out of range\n", i, tmp[i]);
+			return -EINVAL;
+		}
+
+		if (used[tmp[i]]) {
+			dev_dbg(dp->dev, "data-lanes[%d] = %u is duplicate\n", i, tmp[i]);
+			return -EINVAL;
+		}
+
+		used[tmp[i]] = true;
+		map[i] = tmp[i];
+	}
+
+	for (i = 0; i < LANE_COUNT4 && num_lanes < LANE_COUNT4; i++) {
+		if (!used[i])
+			map[num_lanes++] = i;
+	}
+
+	dev_dbg(dp->dev, "Using parsed lane map: <%u %u %u %u>\n", map[0], map[1], map[2], map[3]);
+
+	memcpy(video_info->lane_map, map, sizeof(map));
+
+	return 0;
+}
+
 static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
 {
 	struct device_node *dp_node = dp->dev->of_node;
@@ -1274,6 +1327,9 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
 		break;
 	}
 
+	if (analogix_dp_dt_parse_lanes_map(dp))
+		dev_dbg(dp->dev, "No valid data-lanes found, using default lane map\n");
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
index 17347448c6b0..634fad241e69 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
@@ -137,6 +137,8 @@ struct video_info {
 
 	int max_link_rate;
 	enum link_lane_count_type max_lane_count;
+
+	u32 lane_map[LANE_COUNT4];
 };
 
 struct link_train {
@@ -175,7 +177,7 @@ struct analogix_dp_device {
 /* analogix_dp_reg.c */
 void analogix_dp_enable_video_mute(struct analogix_dp_device *dp, bool enable);
 void analogix_dp_stop_video(struct analogix_dp_device *dp);
-void analogix_dp_lane_swap(struct analogix_dp_device *dp, bool enable);
+void analogix_dp_lane_mapping(struct analogix_dp_device *dp);
 void analogix_dp_init_analog_param(struct analogix_dp_device *dp);
 void analogix_dp_init_interrupt(struct analogix_dp_device *dp);
 void analogix_dp_reset(struct analogix_dp_device *dp);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index 38fd8d5014d2..45c7652645a1 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -48,16 +48,15 @@ void analogix_dp_stop_video(struct analogix_dp_device *dp)
 	writel(reg, dp->reg_base + ANALOGIX_DP_VIDEO_CTL_1);
 }
 
-void analogix_dp_lane_swap(struct analogix_dp_device *dp, bool enable)
+void analogix_dp_lane_mapping(struct analogix_dp_device *dp)
 {
+	u32 *lane_map = dp->video_info.lane_map;
 	u32 reg;
 
-	if (enable)
-		reg = LANE3_MAP_LOGIC_LANE_0 | LANE2_MAP_LOGIC_LANE_1 |
-		      LANE1_MAP_LOGIC_LANE_2 | LANE0_MAP_LOGIC_LANE_3;
-	else
-		reg = LANE3_MAP_LOGIC_LANE_3 | LANE2_MAP_LOGIC_LANE_2 |
-		      LANE1_MAP_LOGIC_LANE_1 | LANE0_MAP_LOGIC_LANE_0;
+	reg = lane_map[0] << LANE0_MAP_SHIFT;
+	reg |= lane_map[1] << LANE1_MAP_SHIFT;
+	reg |= lane_map[2] << LANE2_MAP_SHIFT;
+	reg |= lane_map[3] << LANE3_MAP_SHIFT;
 
 	writel(reg, dp->reg_base + ANALOGIX_DP_LANE_MAP);
 }
@@ -140,7 +139,7 @@ void analogix_dp_reset(struct analogix_dp_device *dp)
 
 	usleep_range(20, 30);
 
-	analogix_dp_lane_swap(dp, 0);
+	analogix_dp_lane_mapping(dp);
 
 	writel(0x0, dp->reg_base + ANALOGIX_DP_SYS_CTL_1);
 	writel(0x40, dp->reg_base + ANALOGIX_DP_SYS_CTL_2);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h
index 12735139046c..ac914e37089b 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.h
@@ -209,6 +209,10 @@
 #define LANE0_MAP_LOGIC_LANE_1			(0x1 << 0)
 #define LANE0_MAP_LOGIC_LANE_2			(0x2 << 0)
 #define LANE0_MAP_LOGIC_LANE_3			(0x3 << 0)
+#define LANE3_MAP_SHIFT				(6)
+#define LANE2_MAP_SHIFT				(4)
+#define LANE1_MAP_SHIFT				(2)
+#define LANE0_MAP_SHIFT				(0)
 
 /* ANALOGIX_DP_ANALOG_CTL_1 */
 #define TX_TERMINAL_CTRL_50_OHM			(0x1 << 4)
-- 
2.34.1

Re: [PATCH v4 1/3] dt-bindings: display: bridge: analogix-dp: Add data-lanes support for endpoint

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 3497 bytes --]

On Fri, May 29, 2026 at 12:05:28PM +0800, Damon Ding wrote:
> Add data-lanes property support to the port@1 endpoint for physical
> lane mapping configuration.
> 
> Lane mapping is mainly used for below scenarios:
> 1. Correct PCB lane swap and differential line routing crossover
>    without hardware changes;
> 2. Adapt mismatched lane pin definitions between SoC and eDP panel;
> 3. Support multiple panel hardware variants on the same board
>    by configuring data-lanes in device tree only.
> 
> Additionally, add data-lanes setting in Rockchip eDP DT node example
> to show actual lane mapping usage.
> 
> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>

Not entirely sure if this is correct, but I'll leave that decision up to
the display folks who know the hardware.
pw-bot: not-applicable
Acked-by: Conor Dooley <conor.dooley@microchip.com>

Cheers,
Conor.

> 
> ---
> 
> Changes in v2:
> - Add lane mapping application scenarios in commit message.
> - Remove redundant deprecated property 'data-lanes' for eDP node.
> - Update port@1 $ref to /schemas/graph.yaml#/$defs/port-base.
> 
> Changes in v3:
> - Squash data-lanes adjustment of Rockchip eDP DT example into this
>   commit.
> - Add unevaluatedProperties: false to both the port@1 and endpoint
>   nodes.
> ---
>  .../bindings/display/bridge/analogix,dp.yaml  | 19 ++++++++++++++-----
>  .../rockchip/rockchip,analogix-dp.yaml        |  1 +
>  2 files changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml b/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml
> index 62f0521b0924..ecf206871cdd 100644
> --- a/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/analogix,dp.yaml
> @@ -42,13 +42,22 @@ properties:
>      properties:
>        port@0:
>          $ref: /schemas/graph.yaml#/properties/port
> -        description:
> -          Input node to receive pixel data.
> +        description: Input node to receive pixel data.
>  
>        port@1:
> -        $ref: /schemas/graph.yaml#/properties/port
> -        description:
> -          Port node with one endpoint connected to a dp-connector node.
> +        $ref: /schemas/graph.yaml#/$defs/port-base
> +        unevaluatedProperties: false
> +        description: Port node with one endpoint connected to sink device node.
> +        properties:
> +          endpoint:
> +            $ref: /schemas/media/video-interfaces.yaml#
> +            unevaluatedProperties: false
> +            properties:
> +              data-lanes:
> +                minItems: 1
> +                maxItems: 4
> +                items:
> +                  enum: [ 0, 1, 2, 3 ]
>  
>      required:
>        - port@0
> diff --git a/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml b/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml
> index d99b23b88cc5..f690ee393fdb 100644
> --- a/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml
> +++ b/Documentation/devicetree/bindings/display/rockchip/rockchip,analogix-dp.yaml
> @@ -117,6 +117,7 @@ examples:
>            reg = <1>;
>  
>            edp_out_panel: endpoint {
> +            data-lanes = <0 1>;
>              remote-endpoint = <&panel_in_edp>;
>            };
>          };
> -- 
> 2.34.1
> 
> 

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Re: [PATCH v4 2/3] drm/bridge: analogix_dp: Add validation for samsung,lane-count property

[Luca Ceresoli]

On Fri, 29 May 2026 12:05:29 +0800, Damon Ding <damon.ding@rock-chips.com> wrote:

Hello Damon,

>
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> index 8cf6b73bceac..699a7f380c56 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> @@ -1260,8 +1261,16 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
>  		 */
>  		of_property_read_u32(dp_node, "samsung,link-rate",
>  				     &video_info->max_link_rate);
> -		of_property_read_u32(dp_node, "samsung,lane-count",
> -				     &video_info->max_lane_count);
> +		ret = of_property_read_u32(dp_node, "samsung,lane-count",
> +					   &video_info->max_lane_count);
> +		if (!ret) {
> +			if (video_info->max_lane_count == 0 ||
> +			    video_info->max_lane_count > LANE_COUNT4) {

This sashiko report seems to me valid.

But I'n no DP expert, I have no idea whether this ther one is valid.

> +				dev_err(dp->dev, "samsung,lane-count = %d is out of range\n",
> +					video_info->max_lane_count);
> +				return -EINVAL;
> +			}
> +		}

As reported by sashiko, 'count == 0' should be 'count <= 0', being an enum.

Additionally I'd avoid the nested if, and I think using dev_err_probe() is
correct here (we are only called by probe functions), so it all could
become:

   if (ret || count <= 0 || count > LANE_COUNT0)
        return dev_err_probe(...);

There are other sashiko reports to patch 3, and at least one seems valid to
me. Can you either fix them in the next iteration or elaborate on why the
code is correct there?

Thanks!

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v4 2/3] drm/bridge: analogix_dp: Add validation for samsung,lane-count property

[Luca Ceresoli]

On Sat May 30, 2026 at 3:33 PM CEST, Luca Ceresoli wrote:
> On Fri, 29 May 2026 12:05:29 +0800, Damon Ding <damon.ding@rock-chips.com> wrote:
>
> Hello Damon,
>
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index 8cf6b73bceac..699a7f380c56 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -1260,8 +1261,16 @@ static int analogix_dp_dt_parse_pdata(struct analogix_dp_device *dp)
>>  		 */
>>  		of_property_read_u32(dp_node, "samsung,link-rate",
>>  				     &video_info->max_link_rate);
>> -		of_property_read_u32(dp_node, "samsung,lane-count",
>> -				     &video_info->max_lane_count);
>> +		ret = of_property_read_u32(dp_node, "samsung,lane-count",
>> +					   &video_info->max_lane_count);
>> +		if (!ret) {
>> +			if (video_info->max_lane_count == 0 ||
>> +			    video_info->max_lane_count > LANE_COUNT4) {
>
> This sashiko report seems to me valid.

Meh, messed up with 'b4 review' :-/ Apologies

"This sashiko report" [0] was about an enum being signed, so '== 0' could miss
negative numbers coming from bogus DT values higher than 1^31.

>
> But I'n no DP expert, I have no idea whether this ther one is valid.

And this was about "Additionally, does this check inadvertently allow 3,
which is an invalid DisplayPort lane count?"

>> +				dev_err(dp->dev, "samsung,lane-count = %d is out of range\n",
>> +					video_info->max_lane_count);
>> +				return -EINVAL;
>> +			}
>> +		}
>
> As reported by sashiko, 'count == 0' should be 'count <= 0', being an enum.
>
> Additionally I'd avoid the nested if, and I think using dev_err_probe() is
> correct here (we are only called by probe functions), so it all could
> become:
>
>    if (ret || count <= 0 || count > LANE_COUNT0)
>         return dev_err_probe(...);
>
> There are other sashiko reports to patch 3, and at least one seems valid to
> me. Can you either fix them in the next iteration or elaborate on why the
> code is correct there?
>
> Thanks!


[0] https://sashiko.dev/#/patchset/20260529040530.741336-1-damon.ding%40rock-chips.com

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com