[PATCH v3 0/2] Add NEC LCD Technologies NL6448BC33-70C Panel Support

[PATCH v3 0/2] Add NEC LCD Technologies NL6448BC33-70C Panel Support

[Steffen Trumtrar]

Add support for the above mentioned LCD panel from NEC.

---
Changes in v3:
- fix bus_format for LVDS type
- Include feedback from Sashiko AI review: https://sashiko.dev/#/patchset/20260515-v7-1-topic-panel-simple-nl6448bc33-v2-0-74ab0baa1817@pengutronix.de?part=2
- Link to v2: https://patch.msgid.link/20260515-v7-1-topic-panel-simple-nl6448bc33-v2-0-74ab0baa1817@pengutronix.de

Changes in v2:
- fix .size settings
- set connector_type
- Include feedback from Sashiko AI review: https://sashiko.dev/#/patchset/20260513-v7-1-topic-panel-simple-nl6448bc33-v1-0-9bd4b7d0eac0@pengutronix.de?part=2
- Link to v1: https://patch.msgid.link/20260513-v7-1-topic-panel-simple-nl6448bc33-v1-0-9bd4b7d0eac0@pengutronix.de

To: Neil Armstrong <neil.armstrong@linaro.org>
To: Jessica Zhang <jesszhan0024@gmail.com>
To: David Airlie <airlied@gmail.com>
To: Simona Vetter <simona@ffwll.ch>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Maxime Ripard <mripard@kernel.org>
To: Thomas Zimmermann <tzimmermann@suse.de>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Thierry Reding <thierry.reding@gmail.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: dri-devel@lists.freedesktop.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

---
Steffen Trumtrar (2):
      dt-bindings: display: simple: Add NEC NL6448BC33-70C panel
      drm/panel: simple: add NEC NL6448BC33-70C

 .../bindings/display/panel/panel-simple.yaml       |  2 ++
 drivers/gpu/drm/panel/panel-simple.c               | 29 ++++++++++++++++++++++
 2 files changed, 31 insertions(+)
---
base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
change-id: 20260513-v7-1-topic-panel-simple-nl6448bc33-c36e33b18ab1

Best regards,
--  
Steffen Trumtrar <s.trumtrar@pengutronix.de>

[PATCH v3 1/2] dt-bindings: display: simple: Add NEC NL6448BC33-70C panel

[Steffen Trumtrar]

Add the NEC LCD Technologies,Ltd. NL6448BC33-70C 10.4" 640x480 LCD panel.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
---
 Documentation/devicetree/bindings/display/panel/panel-simple.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/panel-simple.yaml b/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
index 3e41ed0ef5d51..96d218f78b0be 100644
--- a/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
+++ b/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
@@ -232,6 +232,8 @@ properties:
       - nec,nl12880bc20-05
         # NEC LCD Technologies,Ltd. WQVGA TFT LCD panel
       - nec,nl4827hc19-05b
+        # NEC LCD Technologies,Ltd. VGA TFT LCD panel
+      - nec,nl6448bc33-70c
         # Netron-DY E231732 7.0" WSVGA TFT LCD panel
       - netron-dy,e231732
         # Newhaven Display International 480 x 272 TFT LCD panel

-- 
2.53.0

[PATCH v3 2/2] drm/panel: simple: add NEC NL6448BC33-70C

[Steffen Trumtrar]

Add NEC NL6448BC33-70C 10.4" 640x480 LCD module support.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
 drivers/gpu/drm/panel/panel-simple.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 236bd56208ccf..0bf50b1ed69e6 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -3659,6 +3659,32 @@ static const struct panel_desc nec_nl4827hc19_05b = {
 	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
 };
 
+static const struct drm_display_mode nec_nl6448bc33_70c_mode = {
+	.clock = 25175,
+	.hdisplay = 640,
+	.hsync_start = 640 + 16,
+	.hsync_end = 640 + 16 + 48,
+	.htotal = 640 + 16 + 48 + 96,
+	.vdisplay = 480,
+	.vsync_start = 480 + 2,
+	.vsync_end = 480 + 2 + 31,
+	.vtotal = 480 + 2 + 31 + 31,
+	.flags = DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_PHSYNC,
+};
+
+static const struct panel_desc nec_nl6448bc33_70c = {
+	.modes = &nec_nl6448bc33_70c_mode,
+	.num_modes = 1,
+	.bpc = 6,
+	.size = {
+		.width = 211,
+		.height = 158,
+	},
+	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
+	.connector_type = DRM_MODE_CONNECTOR_LVDS,
+};
+
 static const struct drm_display_mode netron_dy_e231732_mode = {
 	.clock = 66000,
 	.hdisplay = 1024,
@@ -5520,6 +5546,9 @@ static const struct of_device_id platform_of_match[] = {
 	}, {
 		.compatible = "nec,nl4827hc19-05b",
 		.data = &nec_nl4827hc19_05b,
+	}, {
+		.compatible = "nec,nl6448bc33-70c",
+		.data = &nec_nl6448bc33_70c,
 	}, {
 		.compatible = "netron-dy,e231732",
 		.data = &netron_dy_e231732,

-- 
2.53.0

Re: [PATCH v3 2/2] drm/panel: simple: add NEC NL6448BC33-70C

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The horizontal and vertical display timings incorrectly map front porch, back porch, and sync pulse length values, swapping them in the additive configuration.
--

commit 7c39ee64a0bc09df1a4fc9c15180db0749bff494
Author: Steffen Trumtrar <s.trumtrar@pengutronix.de>

drm/panel: simple: add NEC NL6448BC33-70C

This commit adds support for the NEC NL6448BC33-70C 10.4" 640x480 LCD module.

> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 236bd56208ccf..0bf50b1ed69e6 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -3659,6 +3659,32 @@ static const struct panel_desc nec_nl4827hc19_05b = {
[ ... ]
> +static const struct drm_display_mode nec_nl6448bc33_70c_mode = {
> +	.clock = 25175,
> +	.hdisplay = 640,
> +	.hsync_start = 640 + 16,
> +	.hsync_end = 640 + 16 + 48,
> +	.htotal = 640 + 16 + 48 + 96,

Are the sync pulse length and back porch values transposed here?

The additive timing formula is hsync_end = hsync_start + hsync_len and
htotal = hsync_end + hback_porch. This configuration results in an hsync_len
of 48 and an hback_porch of 96. Standard 640x480 timing with a 25.175 MHz
clock typically uses an hsync_len of 96 and an hback_porch of 48.

> +	.vdisplay = 480,
> +	.vsync_start = 480 + 2,
> +	.vsync_end = 480 + 2 + 31,
> +	.vtotal = 480 + 2 + 31 + 31,

Does this code similarly transpose the vertical timings?

This setup yields a vsync_len of 31 lines, which seems abnormally large
for an LCD panel. Could this cause the panel to fail to sync or incorrectly
shift the displayed image?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260518-v7-1-topic-panel-simple-nl6448bc33-v3-0-21ea14a6e835@pengutronix.de?part=2

Re: [PATCH v3 2/2] drm/panel: simple: add NEC NL6448BC33-70C

[Neil Armstrong]

On 5/18/26 09:47, Steffen Trumtrar wrote:
> Add NEC NL6448BC33-70C 10.4" 640x480 LCD module support.
> 
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> ---
>   drivers/gpu/drm/panel/panel-simple.c | 29 +++++++++++++++++++++++++++++
>   1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 236bd56208ccf..0bf50b1ed69e6 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -3659,6 +3659,32 @@ static const struct panel_desc nec_nl4827hc19_05b = {
>   	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
>   };
>   
> +static const struct drm_display_mode nec_nl6448bc33_70c_mode = {
> +	.clock = 25175,
> +	.hdisplay = 640,
> +	.hsync_start = 640 + 16,
> +	.hsync_end = 640 + 16 + 48,
> +	.htotal = 640 + 16 + 48 + 96,
> +	.vdisplay = 480,
> +	.vsync_start = 480 + 2,
> +	.vsync_end = 480 + 2 + 31,
> +	.vtotal = 480 + 2 + 31 + 31,
> +	.flags = DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_PHSYNC,
> +};
> +
> +static const struct panel_desc nec_nl6448bc33_70c = {
> +	.modes = &nec_nl6448bc33_70c_mode,
> +	.num_modes = 1,
> +	.bpc = 6,
> +	.size = {
> +		.width = 211,
> +		.height = 158,
> +	},
> +	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> +	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> +};
> +
>   static const struct drm_display_mode netron_dy_e231732_mode = {
>   	.clock = 66000,
>   	.hdisplay = 1024,
> @@ -5520,6 +5546,9 @@ static const struct of_device_id platform_of_match[] = {
>   	}, {
>   		.compatible = "nec,nl4827hc19-05b",
>   		.data = &nec_nl4827hc19_05b,
> +	}, {
> +		.compatible = "nec,nl6448bc33-70c",
> +		.data = &nec_nl6448bc33_70c,
>   	}, {
>   		.compatible = "netron-dy,e231732",
>   		.data = &netron_dy_e231732,
> 

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Thanks,
Neil