linux-kernel - Re: [PATCH v1 16/17] drm/mediatek: dpi: Add mt8195 hdmi to DPI driver

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Date:   Tue, 27 Sep 2022 06:34:34 -0700
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 16/17] drm/mediatek: dpi: Add mt8195 hdmi to DPI driver

On Tue, 20 Sep 2022 14:22, AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>Il 19/09/22 18:56, Guillaume Ranquet ha scritto:
>> Add the DPI1 hdmi path support in mtk dpi driver
>>
>> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
>> index 630a4e301ef6..91212b7610e8 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
>> @@ -15,7 +15,10 @@
>>   #include <linux/of_graph.h>
>>   #include <linux/pinctrl/consumer.h>
>>   #include <linux/platform_device.h>
>> +#include <linux/reset.h>
>>   #include <linux/types.h>
>> +#include <linux/regmap.h>
>> +#include <linux/mfd/syscon.h>
>>
>>   #include <video/videomode.h>
>>
>> @@ -66,10 +69,14 @@ struct mtk_dpi {
>>   	struct drm_bridge *next_bridge;
>>   	struct drm_connector *connector;
>>   	void __iomem *regs;
>> +	struct reset_control *reset_ctl;
>>   	struct device *dev;
>>   	struct clk *engine_clk;
>> +	struct clk *dpi_ck_cg;
>>   	struct clk *pixel_clk;
>> +	struct clk *dpi_sel_clk;
>>   	struct clk *tvd_clk;
>> +	struct clk *hdmi_cg;
>
>
>You're adding new clocks and then you're making *all clocks*, including the
>already existing ones... optional.
>
>That looks seriously odd.... can you please give a devicetree example for
>MT8195 in the next version, perhaps in the cover letter?
>
>Would also make it easier to test this entire big series.
>
>Regards,
>Angelo
>

The clock names are different for MT8195 HDMI than for the legacy DP.
Making everything optional might not have been a smart move.
I'll try to think of something else to make it look less odd.

The device tree I'm using to test things is rather "hackish" and has a bunch of
changes from what is found on linux-next.
I think Jason and Nancy are due to upstream those patches.

I'll try to include something minimal for you to test.
Otherwise would a public branch containing everything work for you?

Thx,
Guillaume.