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From:   Robert Foss <robert.foss@linaro.org>
Date:   Tue, 6 Apr 2021 12:21:31 +0200
Message-ID: <CAG3jFyvC6ozPxQ=TPdPgLAugKky5AhOZGJSiw0Dc3Kn5Pba0cA@mail.gmail.com>
Subject: Re: [PATCH -next] drm/bridge: lt8912b: DRM_LONTIUM_LT8912B select GPIOLIB
To:     Zhang Jianhua <zhangjianhua18@huawei.com>
Cc:     Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        johnny.chenyi@huawei.com, heying24@huawei.com
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Hey Zhang

On Tue, 6 Apr 2021 at 11:07, Zhang Jianhua <zhangjianhua18@huawei.com> wrot=
e:
>
> If CONFIG_DRM_LONTIUM_LT8912B=3Dy, the following errors will be seen whil=
e
> compiling lontium-lt8912b.c
>
> drivers/gpu/drm/bridge/lontium-lt8912b.c: In function
> =E2=80=98lt8912_hard_power_on=E2=80=99:
> drivers/gpu/drm/bridge/lontium-lt8912b.c:252:2: error: implicit
> declaration of function =E2=80=98gpiod_set_value_cansleep=E2=80=99; did y=
ou mean
> =E2=80=98gpio_set_value_cansleep=E2=80=99? [-Werror=3Dimplicit-function-d=
eclaration]
>   gpiod_set_value_cansleep(lt->gp_reset, 0);
>   ^~~~~~~~~~~~~~~~~~~~~~~~
>   gpio_set_value_cansleep
> drivers/gpu/drm/bridge/lontium-lt8912b.c: In function =E2=80=98lt8912_par=
se_dt=E2=80=99:
> drivers/gpu/drm/bridge/lontium-lt8912b.c:628:13: error: implicit
> declaration of function =E2=80=98devm_gpiod_get_optional=E2=80=99; did yo=
u mean
> =E2=80=98devm_gpio_request_one=E2=80=99? [-Werror=3Dimplicit-function-dec=
laration]
>   gp_reset =3D devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>              ^~~~~~~~~~~~~~~~~~~~~~~
>              devm_gpio_request_one
> drivers/gpu/drm/bridge/lontium-lt8912b.c:628:51: error: =E2=80=98GPIOD_OU=
T_HIGH=E2=80=99
> undeclared (first use in this function); did you mean =E2=80=98GPIOF_INIT=
_HIGH=E2=80=99?
>   gp_reset =3D devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
>                                                    ^~~~~~~~~~~~~~
>                                                    GPIOF_INIT_HIGH
>
> Signed-off-by: Zhang Jianhua <zhangjianhua18@huawei.com>
> ---
>  drivers/gpu/drm/bridge/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kcon=
fig
> index dba62f92d051..caa9658ec933 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -67,6 +67,7 @@ config DRM_LONTIUM_LT8912B
>         select DRM_PANEL_BRIDGE
>         select DRM_KMS_HELPER
>         select REGMAP_I2C
> +       select GPIOLIB

This appears like the right fix for this problem. However, a number of
drm/bridge drivers seem to call both gpio_set_value_cansleep() and
devm_gpiod_get_optional() without having the GPIOLIB kconfig option
selected so this can't be a new issue. Maybe some more investigation
is in order.