linux-kernel - Re: [PATCH v1 2/4] drm/panel: boe-tv101wum-nl6: Support for BOE nv110wum-l60 MIPI-DSI panel

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Date: Thu, 18 Apr 2024 16:00:24 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: cong yang <yangcong5@...qin.corp-partner.google.com>
Cc: Doug Anderson <dianders@...omium.org>, sam@...nborg.org, neil.armstrong@...aro.org, 
	daniel@...ll.ch, airlied@...il.com, robh+dt@...nel.org, 
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, 
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/4] drm/panel: boe-tv101wum-nl6: Support for BOE
 nv110wum-l60 MIPI-DSI panel

On Thu, Apr 18, 2024 at 2:42 PM cong yang
<yangcong5@...qin.corp-partner.google.com> wrote:

> I learned from himax that even if the same controller is used with
> different glasses, the corresponding parameters are not fixed.
>
> For example: _INIT_DCS_CMD(0xB9, 0x83, 0x10, 0x21, 0x55, 0x00),
>
> even in the group initial code, the same register will be loaded with
> parameters twice.
(...)
> So assuming that the registers of the two screens is the same now,
> it cannot be set as a common parameter.
> Otherwise, it may be a bit troublesome for the maintainers.
>
> If necessary, I can break out starry_himax83102_j02, boe_nv110wum and
> ivo_t109nw41
> as separate driver. Then add some define to these registers.

Why would you do a separate driver per panel despite they have
the same display controller? I don't get it.

Use one driver, use different compatible strings for the different
panels and use the corresponding sequence for each panel
selected by compatible string.

For example, see drivers/gpu/drm/panel/panel-novatek-nt35510.c:

static const struct of_device_id nt35510_of_match[] = {
        {
                .compatible = "frida,frd400b25025",
                .data = &nt35510_frida_frd400b25025,
        },
        {
                .compatible = "hydis,hva40wv1",
                .data = &nt35510_hydis_hva40wv1,
        },
        { }
};


Take some inspiration from this driver and how we parameterize
the different data depending on compatible string.

Yours,
Linus Walleij