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

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The `size` field in `panel_desc` is incorrectly populated with the physical outline dimensions of the module rather than the active display area, which will cause incorrect DPI calculations in userspace.
- [Low] The `connector_type` field is uninitialized in the `nec_nl6448bc33_70c` panel descriptor, which will trigger a kernel warning during probe.
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commit d2a2636831b20ec008ea25a3fcc3144f386ad581
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
to the panel-simple driver.

> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 236bd56208ccf..bbbbdd399d1c3 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c

[ ... ]

> +static const struct panel_desc nec_nl6448bc33_70c = {
> +	.modes = &nec_nl6448bc33_70c_mode,
> +	.num_modes = 1,
> +	.bpc = 6,
> +	.size = {
> +		.width = 243,
> +		.height = 185,
> +	},

The commit message specifies this is a 10.4" panel, but these dimensions
(243x185 mm) yield a diagonal of approximately 12.0 inches. Are these the
physical module outline dimensions instead of the active display area?

The DRM subsystem propagates width_mm and height_mm to
connector->display_info for userspace DPI scaling calculations. Using the
mechanical outline instead of the active area (which is typically around
211x158 mm for a 10.4" 4:3 panel) might result in incorrect UI scaling.

> +	.bus_format = MEDIA_BUS_FMT_RGB666_1X18,
> +	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> +};

Is it intentional to omit the connector_type field here?

When this field is omitted, panel_simple_probe() will emit a kernel
warning saying "Specify missing connector_type" before falling back to
DRM_MODE_CONNECTOR_DPI. Specifying the correct connector type explicitly
prevents this warning during boot.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260513-v7-1-topic-panel-simple-nl6448bc33-v1-0-9bd4b7d0eac0@pengutronix.de?part=2