linux-kernel - Re: [PATCH 4/5] drm: convert drivers to use drm_of_find_panel_or

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Date:   Sun, 5 Feb 2017 16:25:39 -0600
From:   Rob Herring <robh@...nel.org>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Marek Vasut <marex@...x.de>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Sean Paul <seanpaul@...omium.org>,
        DRI mailing list <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Archit Taneja <architt@...eaurora.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Inki Dae <inki.dae@...sung.com>,
        Joonyoung Shim <jy0922.shim@...sung.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Stefan Agner <stefan@...er.ch>,
        Alison Wang <alison.wang@...escale.com>,
        Xinliang Liu <z.liuxinliang@...ilicon.com>,
        Rongrong Zou <zourongrong@...il.com>,
        Xinwei Kong <kong.kongxinwei@...ilicon.com>,
        Chen Feng <puck.chen@...ilicon.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        CK Hu <ck.hu@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Mark Yao <mark.yao@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Liviu Dudau <liviu.dudau@....com>,
        Mali DP Maintainers <malidp@...s.arm.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        Kevin Hilman <khilman@...libre.com>,
        Rob Clark <robdclark@...il.com>, Jyri Sarha <jsarha@...com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Eric Anholt <eric@...olt.net>,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: Re: [PATCH 4/5] drm: convert drivers to use drm_of_find_panel_or_bridge

On Sat, Feb 4, 2017 at 2:26 PM, Fabio Estevam <festevam@...il.com> wrote:
> Hi Rob,
>
> On Sat, Feb 4, 2017 at 1:36 AM, Rob Herring <robh@...nel.org> wrote:
>
>> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_out.c b/drivers/gpu/drm/mxsfb/mxsfb_out.c
>> index fa8d17399407..f7d729aa09bd 100644
>> --- a/drivers/gpu/drm/mxsfb/mxsfb_out.c
>> +++ b/drivers/gpu/drm/mxsfb/mxsfb_out.c
>> @@ -19,6 +19,7 @@
>>  #include <drm/drm_crtc_helper.h>
>>  #include <drm/drm_fb_cma_helper.h>
>>  #include <drm/drm_gem_cma_helper.h>
>> +#include <drm/drm_of.h>
>>  #include <drm/drm_panel.h>
>>  #include <drm/drm_plane_helper.h>
>>  #include <drm/drm_simple_kms_helper.h>
>> @@ -82,20 +83,15 @@ static const struct drm_connector_funcs mxsfb_panel_connector_funcs = {
>>         .atomic_destroy_state   = drm_atomic_helper_connector_destroy_state,
>>  };
>>
>> -static int mxsfb_attach_endpoint(struct drm_device *drm,
>> -                                const struct of_endpoint *ep)
>> +int mxsfb_create_output(struct drm_device *drm)
>>  {
>>         struct mxsfb_drm_private *mxsfb = drm->dev_private;
>> -       struct device_node *np;
>>         struct drm_panel *panel;
>> -       int ret = -EPROBE_DEFER;
>> -
>> -       np = of_graph_get_remote_port_parent(ep->local_node);
>> -       panel = of_drm_find_panel(np);
>> -       of_node_put(np);
>> +       int ret;
>>
>> -       if (!panel)
>> -               return -EPROBE_DEFER;
>> +       ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0, &panel, NULL);
>> +       if (ret)
>> +               return ret;
>
> I fixed some build issues of this series and I am trying to use it
> with the mxsfb drm driver.
>
> I would like to add bridge support for this driver, so that I can use
> the TDA19988 HDMI bridge on a imx6sx-udoo-neo-full board.
>
> My dts looks like this:
>
> --- a/arch/arm/boot/dts/imx6sx-udoo-neo.dtsi
> +++ b/arch/arm/boot/dts/imx6sx-udoo-neo.dtsi
> @@ -185,6 +185,41 @@
>         };
>  };
>
> +&i2c3 {
> +       pinctrl-names = "default";
> +       pinctrl-0 = <&pinctrl_i2c3>;
> +       clock-frequency = <100000>;
> +       status = "okay";
> +
> +       hdmi-transmitter@70 {
> +               compatible = "nxp,tda998x";
> +               reg = <0x70>;
> +               pinctrl-0 = <&pinctrl_hdmi>;
> +               pinctrl-names = "default";
> +               interrupt-parent = <&gpio3>;
> +               interrupts = <27 IRQ_TYPE_EDGE_FALLING>;
> +               clocks = <&clks IMX6SX_CLK_CKO2>;
> +
> +               port {
> +                       tda998x_input: endpoint {
> +                               remote-endpoint = <&lcdif1_output>;
> +                       };
> +               };
> +       };
> +};
> +
> +&lcdif1 {
> +       pinctrl-names = "default";
> +       pinctrl-0 = <&pinctrl_lcd>;
> +       status = "okay";
> +
> +       port {
> +               lcdif1_output: endpoint {
> +                       remote-endpoint = <&tda998x_input>;
> +               };
> +       };
> +};
>
> and I changed it to:
>
> ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0, &panel, &bridge);
>
> ,but drm_of_find_panel_or_bridge() always returns -EPROBE_DEFER.
>
> Shouldn't it be able to find the bridge chip in this case? Any ideas
> of what it is missing?

Did the bridge driver probe? This function just checks lists of
registered panels and bridges.

Rob