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From:   Doug Anderson <dianders@chromium.org>
Date:   Tue, 13 Jul 2021 06:41:01 -0700
Message-ID: <CAD=FV=Wn1GU51vqBUZAt4b-_CE4qJpj+Himm8B9CBSn0L6P2XA@mail.gmail.com>
Subject: Re: [PATCH v2] drm/dp: Move panel DP AUX backlight support to drm_dp_helper
To:     Lyude Paul <lyude@redhat.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Robert Foss <robert.foss@linaro.org>
Cc:     Rajeev Nandan <rajeevny@codeaurora.org>,
        =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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Hi,

On Mon, Jul 12, 2021 at 8:02 AM Douglas Anderson <dianders@chromium.org> wr=
ote:
>
> We were getting a depmod error:
>   depmod: ERROR: Cycle detected: drm_kms_helper -> drm -> drm_kms_helper
>
> It looks like the rule is that drm_kms_helper can call into drm, but
> drm can't call into drm_kms_helper. That means we've got to move the
> DP AUX backlight support into drm_dp_helper.
>
> NOTE: as part of this, I didn't try to do any renames of the main
> registration function. Even though it's in the drm_dp_helper, it still
> feels very parallel to drm_panel_of_backlight().
>
> Fixes: 10f7b40e4f30 ("drm/panel: add basic DP AUX backlight support")
> Reported-by: Ville Syrj=C3=A4l=C3=A4 <ville.syrjala@linux.intel.com>
> Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> Note that I've compile tested this, but I don't have a device setup
> yet that uses this code. Since the code is basically the same as it
> was this should be OK, but if Rajeev could confirm that nothing is
> broken that'd be nice.
>
> Changes in v2:
> - Guard new functions by the proper configs.
>
>  drivers/gpu/drm/drm_dp_helper.c | 113 ++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_panel.c     | 108 ------------------------------
>  include/drm/drm_dp_helper.h     |  16 +++++
>  include/drm/drm_panel.h         |   8 ---
>  4 files changed, 129 insertions(+), 116 deletions(-)

Pushed to drm-misc-next with Rajeev's review:

072ed3431f5b drm/dp: Move panel DP AUX backlight support to drm_dp_helper

-Doug