linux-kernel - Re: [PATCH] [v3] drm/sun4i: fix build failure with CONFIG_DRM_SUN8I

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Date:   Wed, 12 Sep 2018 12:25:54 +0100
From:   Matt Hart <matthew.hart@...aro.org>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Chen-Yu Tsai <wens@...e.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>
Subject: Re: [PATCH] [v3] drm/sun4i: fix build failure with CONFIG_DRM_SUN8I_MIXER=m

On 7 September 2018 at 12:42, Maxime Ripard <maxime.ripard@...tlin.com> wrote:
> On Fri, Sep 07, 2018 at 01:26:30PM +0200, Arnd Bergmann wrote:
>> On Fri, Sep 7, 2018 at 11:41 AM Jon Hunter <jonathanh@...dia.com> wrote:
>> >
>> >
>> > On 11/07/18 15:43, Arnd Bergmann wrote:
>> > > Having DRM_SUN4I built-in but DRM_SUN8I_MIXER as a loadable module results in
>> > > a link error, as we try to access a symbol from the sun8i_tcon_top.ko module:
>> > >
>> > > ERROR: "sun8i_tcon_top_of_table" [drivers/gpu/drm/sun4i/sun8i-drm-hdmi.ko] undefined!
>> > > ERROR: "sun8i_tcon_top_of_table" [drivers/gpu/drm/sun4i/sun4i-drm.ko] undefined!
>> > >
>> > > This solves the problem by adding a silent symbol for the tcon_top module,
>> > > building it as a separate module in exactly the cases that we need it,
>> > > but in a way that it is reachable by the other modules.
>> > >
>> > > Fixes: 57e23de02f48 ("drm/sun4i: DW HDMI: Expand algorithm for possible crtcs")
>> > > Fixes: ef0cf6441fbb ("drm/sun4i: Add support for traversing graph with TCON TOP")
>> > > Signed-off-by: Arnd Bergmann <arnd@...db.de>
>> > I am seeing the following on today's -next (20180907) as well the last
>> > few -next versions for that matter ...
>> >
>> > ERROR: "sun8i_tcon_top_de_config" [drivers/gpu/drm/sun4i/sun4i-tcon.ko] undefined!
>> > ERROR: "sun8i_tcon_top_set_hdmi_src" [drivers/gpu/drm/sun4i/sun4i-tcon.ko] undefined!
>> > ERROR: "sun8i_tcon_top_of_table" [drivers/gpu/drm/sun4i/sun4i-tcon.ko] undefined!
>> >
>> > Seems like this issue has cropped up again as Arnd's fix is present. I
>> > am seeing this on ARM64 builds.
>>
>> I have not started build testing on linux-next since the merge window, but
>> looking at the changes that got queued up, I find commits cf77d79b4e29
>> ("drm/sun4i: tcon: Add another way for matching mixers with tcon") and
>> 0305189afb32 ("drm/sun4i: tcon: Add support for R40 TCON") that both
>> introduced a reference to the tcon_top file from sun4i_tcon.c.
>>
>> More IS_ENABLED(CONFIG_DRM_SUN8I_TCON_TOP) checks in
>> the caller like I did in my patch would help, or alternatively one could
>> decide to give up and just always include the TCON_TOP.
>
> Sorry for the breakage.
>
> Can you test:
>
> ----8<----
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index 4834c90b4912..c78cd35a1294 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -974,7 +974,8 @@ static bool sun4i_tcon_connected_to_tcon_top(struct device_node *node)
>
>         remote = of_graph_get_remote_node(node, 0, -1);
>         if (remote) {
> -               ret = !!of_match_node(sun8i_tcon_top_of_table, remote);
> +               ret = !!(IS_ENABLED(CONFIG_DRM_SUN8I_TCON_TOP) &&
> +                        of_match_node(sun8i_tcon_top_of_table, remote));
>                 of_node_put(remote);
>         }
>
> @@ -1402,13 +1403,20 @@ static int sun8i_r40_tcon_tv_set_mux(struct sun4i_tcon *tcon,
>         if (!pdev)
>                 return -EINVAL;
>
> -       if (encoder->encoder_type == DRM_MODE_ENCODER_TMDS) {
> +       if (IS_ENABLED(CONFIG_DRM_SUN8I_TCON_TOP) &&
> +           encoder->encoder_type == DRM_MODE_ENCODER_TMDS) {
>                 ret = sun8i_tcon_top_set_hdmi_src(&pdev->dev, id);
>                 if (ret)
>                         return ret;
>         }
>
> -       return sun8i_tcon_top_de_config(&pdev->dev, tcon->id, id);
> +       if (IS_ENABLED(CONFIG_DRM_SUN8I_TCON_TOP)) {
> +               ret = sun8i_tcon_top_de_config(&pdev->dev, tcon->id, id);
> +               if (ret)
> +                       return ret;
> +       }
> +
> +       return 0;
>  }
>
>  static const struct sun4i_tcon_quirks sun4i_a10_quirks = {
> ----8<----

Works for me, and still broken in todays next

>
> Thanks!
> Maxime
>
> --
> Maxime Ripard, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com