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Date:   Thu, 3 Feb 2022 21:14:30 +0100
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Thomas Zimmermann <tzimmermann@suse.de>
Cc:     thierry.reding@gmail.com, airlied@linux.ie, daniel@ffwll.ch,
        lyude@redhat.com, linus.walleij@linaro.org, dianders@chromium.org,
        ardb@kernel.org, naresh.kamboju@linaro.org, arnd@arndb.de,
        rdunlap@infradead.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        Linux Kernel Functional Testing <lkft@linaro.org>
Subject: Re: [PATCH v2] drm/panel: Select DRM_DP_HELPER for DRM_PANEL_EDP
Message-ID: <Yfw3pnlLNuXBo5gD@ravnborg.org>
References: <20220203093922.20754-1-tzimmermann@suse.de>
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On Thu, Feb 03, 2022 at 10:39:22AM +0100, Thomas Zimmermann wrote:
> As reported in [1], DRM_PANEL_EDP depends on DRM_DP_HELPER. Select
> the option to fix the build failure. The error message is shown
> below.
> 
>   arm-linux-gnueabihf-ld: drivers/gpu/drm/panel/panel-edp.o: in function
>     `panel_edp_probe': panel-edp.c:(.text+0xb74): undefined reference to
>     `drm_panel_dp_aux_backlight'
>   make[1]: *** [/builds/linux/Makefile:1222: vmlinux] Error 1
> 
> The issue has been reported before, when DisplayPort helpers were
> hidden behind the option CONFIG_DRM_KMS_HELPER. [2]
> 
> v2:
> 	* fix and expand commit description (Arnd)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Fixes: adb9d5a2cc77 ("drm/dp: Move DisplayPort helpers into separate helper module")
> Fixes: 5f04e7ce392d ("drm/panel-edp: Split eDP panels out of panel-simple")
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Link: https://lore.kernel.org/dri-devel/CA+G9fYvN0NyaVkRQmA1O6rX7H8PPaZrUAD7=RDy33QY9rUU-9g@mail.gmail.com/ # [1]
> Link: https://lore.kernel.org/all/20211117062704.14671-1-rdunlap@infradead.org/ # [2]
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: dri-devel@lists.freedesktop.org

Acked-by: Sam Ravnborg <sam@ravnborg.org>

> ---
>  drivers/gpu/drm/panel/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 434c2861bb40..0aec5a10b064 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -106,6 +106,7 @@ config DRM_PANEL_EDP
>  	depends on PM
>  	select VIDEOMODE_HELPERS
>  	select DRM_DP_AUX_BUS
> +	select DRM_DP_HELPER
>  	help
>  	  DRM panel driver for dumb eDP panels that need at most a regulator and
>  	  a GPIO to be powered up. Optionally a backlight can be attached so
> -- 
> 2.34.1