linux-kernel - Re: [PATCH 3/5] drm/i915/dsi: Init panel-enable GPIO to low when the LCD is initially off

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Date:   Mon, 16 Dec 2019 11:28:09 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Lee Jones <lee.jones@...aro.org>,
        intel-gfx <intel-gfx@...ts.freedesktop.org>,
        "open list:DRM PANEL DRIVERS" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 3/5] drm/i915/dsi: Init panel-enable GPIO to low when the
 LCD is initially off

On Sun, Dec 15, 2019 at 5:38 PM Hans de Goede <hdegoede@...hat.com> wrote:

> When the LCD has not been turned on by the firmware/GOP, because e.g. the
> device was booted with an external monitor connected over HDMI, we should
> not turn on the panel-enable GPIO when we request it.
>
> Turning on the panel-enable GPIO when we request it, means we turn it on
> too early in the init-sequence, which causes some panels to not correctly
> light up.
>
> This commits adds a panel_is_on parameter to intel_dsi_vbt_gpio_init()
> and makes intel_dsi_vbt_gpio_init() set the initial GPIO value accordingly.
>
> This fixes the panel not lighting up on a Thundersoft TST168 tablet when
> booted with an external monitor connected over HDMI.
>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>

Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij