linux-kernel - Re: [PATCH v3 4/8] drm/panel: Add Samsung S6E3FC2X01 DDIC with AMS641RW panel

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Message-ID: <didkbltadu4ql6xcqtjrtf2iguody5bgy6mqlwtbyfgbambaii@mzofzymnfbju>
Date: Thu, 16 Oct 2025 23:12:33 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: david@...t.cz
Cc: Neil Armstrong <neil.armstrong@...aro.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Casey Connolly <casey.connolly@...aro.org>,
        Jessica Zhang <jesszhan0024@...il.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        phone-devel@...r.kernel.org
Subject: Re: [PATCH v3 4/8] drm/panel: Add Samsung S6E3FC2X01 DDIC with
 AMS641RW panel

On Thu, Oct 16, 2025 at 06:16:59PM +0200, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <david@...t.cz>
> 
> Add panel driver used in the OnePlus 6T.
> 
> No datasheet, based mostly on EDK2 init sequence and the downstream driver.
> 
> Note: This driver doesn't use previously mentioned "samsung,s6e3fc2x01"
> by OnePlus 6T device-tree.
> The reason is because DDIC itself without knowing the panel type used
> with it will not give the driver enough information about the panel used,
> as the panel cannot be autodetected.
> While would be more practical to support the original compatible,
> I would like to avoid it, to prevent confusing devs upstreaming DDICs.
> 
> Based on work of:
>   Casey Connolly <casey@...nolly.tech>
>   Joel Selvaraj <foss@...lselvaraj.com>
>   Nia Espera <a5b6@...eup.net>
> 
> Signed-off-by: David Heidelberg <david@...t.cz>
> ---
>  MAINTAINERS                                      |   1 +
>  drivers/gpu/drm/panel/Kconfig                    |  13 +
>  drivers/gpu/drm/panel/Makefile                   |   1 +
>  drivers/gpu/drm/panel/panel-samsung-s6e3fc2x01.c | 399 +++++++++++++++++++++++
>  4 files changed, 414 insertions(+)
> 
> +
> +static const struct drm_display_mode ams641rw_mode = {
> +	.clock = (1080 + 72 + 16 + 36) * (2340 + 32 + 4 + 18) * 60 / 1000,
> +	.hdisplay = 1080,
> +	.hsync_start = 1080 + 72,
> +	.hsync_end = 1080 + 72 + 16,
> +	.htotal = 1080 + 72 + 16 + 36,
> +	.vdisplay = 2340,
> +	.vsync_start = 2340 + 32,
> +	.vsync_end = 2340 + 32 + 4,
> +	.vtotal = 2340 + 32 + 4 + 18,
> +	.width_mm = 68,
> +	.height_mm = 145,
> +};
> +
> +static int s6e3fc2x01_get_modes(struct drm_panel *panel,
> +					struct drm_connector *connector)
> +{
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(connector->dev, &ams641rw_mode);
> +	if (!mode)
> +		return -ENOMEM;
> +
> +	drm_mode_set_name(mode);
> +
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +	connector->display_info.width_mm = mode->width_mm;
> +	connector->display_info.height_mm = mode->height_mm;
> +	drm_mode_probed_add(connector, mode);

drm_connector_helper_get_modes_fixed()

> +
> +	return 1;
> +}
> +
> +
> +static const struct of_device_id s6e3fc2x01_of_match[] = {
> +	/* samsung,s6e3fc2x01 will default to the AMS641RW mode (legacy) */
> +	{ .compatible = "samsung,s6e3fc2x01", .data = &ams641rw_mode },

Is there a need to probide this kind of legacy?

> +	{ .compatible = "samsung,s6e3fc2x01-ams641rw", .data = &ams641rw_mode },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, s6e3fc2x01_of_match);
> +

-- 
With best wishes
Dmitry