linux-kernel - Re: [PATCH v1 09/17] drm/mediatek: hdmi: add connector flag

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Date:   Mon, 3 Oct 2022 17:39:25 +0200
From:   Guillaume Ranquet <granquet@...libre.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Vinod Koul <vkoul@...nel.org>, Stephen Boyd <sboyd@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Rob Herring <robh+dt@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        CK Hu <ck.hu@...iatek.com>, Jitao shi <jitao.shi@...iatek.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Kishon Vijay Abraham I <kishon@...com>
Cc:     linux-mediatek@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org,
        Pablo Sun <pablo.sun@...iatek.com>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Mattijs Korpershoek <mkorpershoek@...libre.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-phy@...ts.infradead.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v1 09/17] drm/mediatek: hdmi: add connector flag

On Tue, 20 Sep 2022 12:38, AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>Il 19/09/22 18:56, Guillaume Ranquet ha scritto:
>> Add a flag to indicate support for an external connector
>>
>> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
>> index 86653ebaacfd..30407603d693 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
>> @@ -199,20 +199,22 @@ int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi, struct platform_device *pdev,
>>   		goto put_device;
>>   	}
>>
>> -	remote = of_graph_get_remote_node(np, 1, 0);
>> -	if (!remote) {
>> -		ret = -EINVAL;
>> -		goto put_device;
>> -	}
>> -
>> -	if (!of_device_is_compatible(remote, "hdmi-connector")) {
>> -		hdmi->next_bridge = of_drm_find_bridge(remote);
>> -		if (!hdmi->next_bridge) {
>> -			dev_err(dev, "Waiting for external bridge\n");
>> -			of_node_put(remote);
>> -			ret = -EPROBE_DEFER;
>> +	if (hdmi->conf->has_connector) {
>
>If MT8195's DPI uses the internal HDMI->DP converter, I say that the external
>DP has HDMI input and DP output.
>Logically, you can't have a HDMI port that's connected to nothing.
>
>Please, rethink this change.
>
>Regards,
>Angelo

Hi Angelo,
Sorry for the late answer.

I have reworked this for V2, to use an hdmi connector device node to "bind"
both the hdmi and hdmi-ddc driver together as with "legacy" code.
So this patch is dropped in V2 (hopefully ready soon).

Just to make things clear, the hardware path on mt8195 is:
DPI1 -> HDMI Tx -> HDMI Phy
DP Intf1 -> DP Tx -> USB Type C Mux -> DP over USB-C

So there's no HDMI->DP converter involved.

Thx,
Guillaume.