drm/panel: simple: add bus-format support for panel-dpi

PATCH Superseded Max Krummenacher 2 participants 6 messages May 18, 2022 – Jun 28, 2022

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Device tree bindings DRM drivers DRM misc DRM panel drivers

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Max Krummenacher

author

2022-05-18 11:56 UTC #0 lore raw

v2 cover drm/panel: simple: add bus-format support for panel-dpi

From: Max Krummenacher <[email protected]>

Commit 4a1d0dbc8332 ("drm/panel: simple: add panel-dpi support") added support for defining a panel from device tree provided data.

However support for setting the bus format is missing, so that with the current implementation a 'panel-dpi' panel can only be used if the driver of the display interface connected can cope with a missing bus_format.

This patch series defines the new property bus-format and adds it to the panel-dpi implementation.

Check initial discussions [1] and [2].
[1] https://lore.kernel.org/all/[email protected]/
[2] https://lore.kernel.org/all/[email protected]/

Changes in v2:
- Fix errors found by dt_binding_check

Max Krummenacher (3):
dt-bindings: display: add new bus-format property for panel-dpi
dt-bindings: display: startek,startek-kd050c: allow bus-format
property
drm/panel: simple: add bus-format support for panel-dpi

 .../bindings/display/panel/panel-dpi.yaml     | 11 +++++
 .../display/panel/startek,startek-kd050c.yaml |  1 +
 drivers/gpu/drm/panel/panel-simple.c          | 43 +++++++++++++++++++
 .../dt-bindings/display/dt-media-bus-format.h | 23 ++++++++++
 4 files changed, 78 insertions(+)
 create mode 100644 include/dt-bindings/display/dt-media-bus-format.h

Signature · 1 line

2.20.1

Max Krummenacher

author

2022-05-18 11:56 UTC #1 lore raw

PATCH v2 1/3 dt-bindings: display: add new bus-format property for panel-dpi

From: Max Krummenacher <[email protected]>

The property is used to set the enum bus_format and infer the bpc for a panel defined by 'panel-dpi'.
This specifies how the panel is connected to the display interface.

Signed-off-by Max Krummenacher <[email protected]>

---

Changes in v2:
- Fix errors found by dt_binding_check

 .../bindings/display/panel/panel-dpi.yaml     | 11 +++++++++
 .../dt-bindings/display/dt-media-bus-format.h | 23 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/dt-bindings/display/dt-media-bus-format.h

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +11 -0

index dae0676b5c6e..a20b5898941e 100644
@@ -21,6 +21,14 @@ properties:
       - {}
       - const: panel-dpi
 
+  bus-format:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: |
+      Describes how the display panel is connected to the display interface.
+      Valid values are defined in <dt-bindings/display/dt-media-bus-format.h>.
+      The mapping between the color/significance of the panel lines to the
+      parallel data lines are defined in [1].
+      [1] https://www.kernel.org/doc/html/v5.17/userspace-api/media/v4l/subdev-formats.html#packed-rgb-formats
   backlight: true
   enable-gpios: true
   height-mm: true

@@ -39,11 +47,14 @@ additionalProperties: false
 
 examples:
   - |
+    #include <dt-bindings/display/dt-media-bus-format.h>
+
     panel {
         compatible = "startek,startek-kd050c", "panel-dpi";
         label = "osddisplay";
         power-supply = <&vcc_supply>;
         backlight = <&backlight>;
+        bus-format = <DT_MEDIA_BUS_FMT_RGB888_1X24>;
 
         port {
             lcd_in: endpoint {

include/dt-bindings/display/dt-media-bus-format.h new file +23 -0

new file mode 100644
index 000000000000..c0f2a7b59aa1
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Copyright 2022 Max Krummenacher <[email protected]>
+ */
+
+#ifndef __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H
+#define __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H
+
+/*
+ * Attention: Keep these macro names in sync with
+ * include/uapi/linux/media-bus-format.h
+ */
+
+#define DT_MEDIA_BUS_FMT_RGB565_1X16		1
+#define DT_MEDIA_BUS_FMT_RGB666_1X18		2
+#define DT_MEDIA_BUS_FMT_RBG888_1X24		3
+#define DT_MEDIA_BUS_FMT_RGB666_1X24_CPADHI	4
+#define DT_MEDIA_BUS_FMT_BGR888_1X24		5
+#define DT_MEDIA_BUS_FMT_GBR888_1X24		6
+#define DT_MEDIA_BUS_FMT_RGB888_1X24		7
+#define DT_MEDIA_BUS_FMT_RGB888_1X32_PADHI	8
+
+#endif /* __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H */

Signature · 1 line

2.20.1

Rob Herring

maintainer

2022-06-01 20:17 UTC #2 lore raw

Re: [PATCH v2 1/3] dt-bindings: display: add new bus-format property for panel-dpi

Quoted 23 lines · Max Krummenacher

From: Max Krummenacher <[email protected]>
The property is used to set the enum bus_format and infer the bpc for a panel defined by 'panel-dpi'.
This specifies how the panel is connected to the display interface.
Signed-off-by Max Krummenacher <[email protected]>
---
Changes in v2:
- Fix errors found by dt_binding_check
 .../bindings/display/panel/panel-dpi.yaml     | 11 +++++++++
 .../dt-bindings/display/dt-media-bus-format.h | 23 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/dt-bindings/display/dt-media-bus-format.h
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +0 -0
index dae0676b5c6e..a20b5898941e 100644

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml properties: · line 25

Quoted 5 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +2 -0

@@ -21,6 +21,14 @@ properties:
       - {}
       - const: panel-dpi
 
+  bus-format:
+    $ref: /schemas/types.yaml#/definitions/uint32

Constraints?

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml properties: · line 30

Quoted 5 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +5 -0

+    description: |
+      Describes how the display panel is connected to the display interface.
+      Valid values are defined in <dt-bindings/display/dt-media-bus-format.h>.
+      The mapping between the color/significance of the panel lines to the
+      parallel data lines are defined in [1].

Just drop the [1] and use a colon.

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml properties: · line 31

Quoted 1 line

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +1 -0
+      [1] https://www.kernel.org/doc/html/v5.17/userspace-api/media/v4l/subdev-formats.html#packed-rgb-formats

Why not just use the V4L number space rather than invent yet another number space?

Need a blank line here too.

Quoted 5 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +0 -0
   backlight: true
   enable-gpios: true
   height-mm: true
@@ -39,11 +47,14 @@ additionalProperties: false
 

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml additionalProperties: false · line 57

Quoted 10 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +3 -0

 examples:
   - |
+    #include <dt-bindings/display/dt-media-bus-format.h>
+
     panel {
         compatible = "startek,startek-kd050c", "panel-dpi";
         label = "osddisplay";
         power-supply = <&vcc_supply>;
         backlight = <&backlight>;
+        bus-format = <DT_MEDIA_BUS_FMT_RGB888_1X24>;

Other properties describing the interface have been put in the endpoint node. This should too I think.

Quoted 36 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +0 -0

         port {
             lcd_in: endpoint {

include/dt-bindings/display/dt-media-bus-format.h new file +23 -0

new file mode 100644
index 000000000000..c0f2a7b59aa1
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Copyright 2022 Max Krummenacher <[email protected]>
+ */
+
+#ifndef __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H
+#define __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H
+
+/*
+ * Attention: Keep these macro names in sync with
+ * include/uapi/linux/media-bus-format.h
+ */
+
+#define DT_MEDIA_BUS_FMT_RGB565_1X16		1
+#define DT_MEDIA_BUS_FMT_RGB666_1X18		2
+#define DT_MEDIA_BUS_FMT_RBG888_1X24		3
+#define DT_MEDIA_BUS_FMT_RGB666_1X24_CPADHI	4
+#define DT_MEDIA_BUS_FMT_BGR888_1X24		5
+#define DT_MEDIA_BUS_FMT_GBR888_1X24		6
+#define DT_MEDIA_BUS_FMT_RGB888_1X24		7
+#define DT_MEDIA_BUS_FMT_RGB888_1X32_PADHI	8
+
+#endif /* __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H */

Signature · 1 line

2.20.1

Max Krummenacher

author

2022-06-28 17:54 UTC #3 lore raw

Re: [PATCH v2 1/3] dt-bindings: display: add new bus-format property for panel-dpi

Hi Rob

Thanks for the feedback.

Quoted 28 lines · Rob Herring

Quoted 26 lines · Max Krummenacher
From: Max Krummenacher <[email protected]>
The property is used to set the enum bus_format and infer the bpc for a panel defined by 'panel-dpi'.
This specifies how the panel is connected to the display interface.
Signed-off-by Max Krummenacher <[email protected]>
---
Changes in v2:
- Fix errors found by dt_binding_check
 .../bindings/display/panel/panel-dpi.yaml     | 11 +++++++++
 .../dt-bindings/display/dt-media-bus-format.h | 23 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 include/dt-bindings/display/dt-media-bus-format.h
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +0 -0
index dae0676b5c6e..a20b5898941e 100644
@@ -21,6 +21,14 @@ properties:
       - {}
       - const: panel-dpi
 

Quoted 4 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml properties: · line 25
Quoted 2 lines
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +2 -0
+  bus-format:
+    $ref: /schemas/types.yaml#/definitions/uint32
Constraints?

Will limit the range to the one used for RGB formats in v3.

Quoted 8 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml properties: · line 30
Quoted 6 lines
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +5 -0
+    description: |
+      Describes how the display panel is connected to the display interface.
+      Valid values are defined in <dt-bindings/display/dt-media-bus-format.h>.
+      The mapping between the color/significance of the panel lines to the
+      parallel data lines are defined in [1].
Just drop the [1] and use a colon.

Done in v3.

Quoted 5 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml properties: · line 31
Quoted 2 lines
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +1 -0
+      [1] https://www.kernel.org/doc/html/v5.17/userspace-api/media/v4l/subdev-formats.html#packed-rgb-formats
Why not just use the V4L number space rather than invent yet another number space?

That was a proposal from here:
https://lore.kernel.org/all/20220323155817.xcsqxothziot7ba3@houat/
But probably it makes more sense to use the number space as is, changed in v3.

Quoted 8 lines

Need a blank line here too.
Quoted 5 lines
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +0 -0
   backlight: true
   enable-gpios: true
   height-mm: true
@@ -39,11 +47,14 @@ additionalProperties: false
 

Quoted 13 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml additionalProperties: false · line 57
Quoted 10 lines
Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +3 -0
 examples:
   - |
+    #include <dt-bindings/display/dt-media-bus-format.h>
+
     panel {
         compatible = "startek,startek-kd050c", "panel-dpi";
         label = "osddisplay";
         power-supply = <&vcc_supply>;
         backlight = <&backlight>;
+        bus-format = <DT_MEDIA_BUS_FMT_RGB888_1X24>;
Other properties describing the interface have been put in the endpoint node. This should too I think.

That makes a lot of sense. Changed to be part of the endpoint node in v3.

Cheers
Max

Quoted 37 lines

Documentation/devicetree/bindings/display/panel/panel-dpi.yaml +0 -0

         port {
             lcd_in: endpoint {

include/dt-bindings/display/dt-media-bus-format.h new file +23 -1

new file mode 100644
index 000000000000..c0f2a7b59aa1
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Copyright 2022 Max Krummenacher <[email protected]>
+ */
+
+#ifndef __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H
+#define __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H
+
+/*
+ * Attention: Keep these macro names in sync with
+ * include/uapi/linux/media-bus-format.h
+ */
+
+#define DT_MEDIA_BUS_FMT_RGB565_1X16         1
+#define DT_MEDIA_BUS_FMT_RGB666_1X18         2
+#define DT_MEDIA_BUS_FMT_RBG888_1X24         3
+#define DT_MEDIA_BUS_FMT_RGB666_1X24_CPADHI  4
+#define DT_MEDIA_BUS_FMT_BGR888_1X24         5
+#define DT_MEDIA_BUS_FMT_GBR888_1X24         6
+#define DT_MEDIA_BUS_FMT_RGB888_1X24         7
+#define DT_MEDIA_BUS_FMT_RGB888_1X32_PADHI   8
+
+#endif /* __DT_BINDINGS_DT_MEDIA_BUS_FORMAT_H */
--

2.20.1

Max Krummenacher

author

2022-05-18 11:56 UTC #4 lore raw

PATCH v2 2/3 dt-bindings: display: startek,startek-kd050c: allow bus-format property

In reply to Max Krummenacher

From: Max Krummenacher <[email protected]>

Allow to specify the optional bus-format property newly added to panel-dpi.

Signed-off-by Max Krummenacher <[email protected]>

---

Changes in v2:
- New commit

 .../bindings/display/panel/startek,startek-kd050c.yaml           | 1 +
 1 file changed, 1 insertion(+)

Documentation/devicetree/bindings/display/panel/startek,startek-kd050c.yaml +1 -0

index fd668640afd1..05306713044e 100644
@@ -19,6 +19,7 @@ properties:
       - {} # panel-dpi, but not listed here to avoid false select
 
   backlight: true
+  bus-format: true
   enable-gpios: true
   height-mm: true
   label: true

Signature · 1 line

2.20.1

Max Krummenacher

author

2022-05-18 11:56 UTC #5 lore raw

PATCH v2 3/3 drm/panel: simple: add bus-format support for panel-dpi

In reply to Max Krummenacher

From: Max Krummenacher <[email protected]>

Evaluate the device tree bus-format property to set bus_format for a 'panel-dpi' panel. Additionally infer the bpc value from the given bus-format.

Valid values for bus-format are found in:
<include/dt-bindings/display/dt-media-bus-format.h>

This completes the addition of panel-dpi to completely specify a panel-simple panel from the device tree.

Signed-off-by Max Krummenacher <[email protected]>

---

Changes in v2:
None

 drivers/gpu/drm/panel/panel-simple.c | 43 ++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

drivers/gpu/drm/panel/panel-simple.c +43 -0

index a34f4198a534..090c60abb014 100644
@@ -21,6 +21,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#include <dt-bindings/display/dt-media-bus-format.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>

@@ -453,6 +454,7 @@ static int panel_dpi_probe(struct device *dev,
 	struct panel_desc *desc;
 	unsigned int bus_flags;
 	struct videomode vm;
+	u32 bus_format;
 	int ret;
 
 	np = dev->of_node;

@@ -477,6 +479,47 @@ static int panel_dpi_probe(struct device *dev,
 	of_property_read_u32(np, "width-mm", &desc->size.width);
 	of_property_read_u32(np, "height-mm", &desc->size.height);
 
+	if (!of_property_read_u32(np, "bus-format", &bus_format)) {
+		/* infer bpc from bus-format */
+		switch (bus_format) {
+		case DT_MEDIA_BUS_FMT_RGB565_1X16:
+			desc->bus_format = MEDIA_BUS_FMT_RGB565_1X16;
+			desc->bpc = 6;
+			break;
+		case DT_MEDIA_BUS_FMT_RGB666_1X18:
+			desc->bus_format = MEDIA_BUS_FMT_RGB666_1X18;
+			desc->bpc = 6;
+			break;
+		case DT_MEDIA_BUS_FMT_RGB666_1X24_CPADHI:
+			desc->bus_format = MEDIA_BUS_FMT_RGB666_1X24_CPADHI;
+			desc->bpc = 6;
+			break;
+		case DT_MEDIA_BUS_FMT_BGR888_1X24:
+			desc->bus_format = MEDIA_BUS_FMT_BGR888_1X24;
+			desc->bpc = 8;
+			break;
+		case DT_MEDIA_BUS_FMT_GBR888_1X24:
+			desc->bus_format = MEDIA_BUS_FMT_GBR888_1X24;
+			desc->bpc = 8;
+			break;
+		case DT_MEDIA_BUS_FMT_RBG888_1X24:
+			desc->bus_format = MEDIA_BUS_FMT_RBG888_1X24;
+			desc->bpc = 8;
+			break;
+		case DT_MEDIA_BUS_FMT_RGB888_1X24:
+			desc->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+			desc->bpc = 8;
+			break;
+		case DT_MEDIA_BUS_FMT_RGB888_1X32_PADHI:
+			desc->bus_format = MEDIA_BUS_FMT_RGB888_1X32_PADHI;
+			desc->bpc = 8;
+			break;
+		default:
+			dev_err(dev, "%pOF: unknown bus-format property\n", np);
+			return -EINVAL;
+		}
+	}
+
 	/* Extract bus_flags from display_timing */
 	bus_flags = 0;
 	vm.flags = timing->flags;

Signature · 1 line

2.20.1