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From:   Guillaume Ranquet <granquet@baylibre.com>
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References: <20220919-v1-0-4844816c9808@baylibre.com> <20220919-v1-5-4844816c9808@baylibre.com>
 <32c4822a-a094-5fa3-c2af-e515bf897937@collabora.com>
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Date:   Tue, 27 Sep 2022 06:06:06 -0700
Message-ID: <CABnWg9vsd7Lk4kR4j-XrgJXAX+sEd3J+oz3hFc4sEuCGRRy8qw@mail.gmail.com>
Subject: Re: [PATCH v1 05/17] drm/mediatek: hdmi: use a syscon/regmap instead
 of iomem
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Vinod Koul <vkoul@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
        David Airlie <airlied@linux.ie>,
        Rob Herring <robh+dt@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        CK Hu <ck.hu@mediatek.com>, Jitao shi <jitao.shi@mediatek.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Kishon Vijay Abraham I <kishon@ti.com>
Cc:     linux-mediatek@lists.infradead.org,
        dri-devel@lists.freedesktop.org,
        Pablo Sun <pablo.sun@mediatek.com>, linux-clk@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Mattijs Korpershoek <mkorpershoek@baylibre.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-phy@lists.infradead.org, devicetree@vger.kernel.org
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On Tue, 20 Sep 2022 12:18, AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>Il 19/09/22 18:56, Guillaume Ranquet ha scritto:
>> To prepare support for newer chips that need to share their address
>> range with a dedicated ddc driver, move to a syscon.
>>
>> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
>> index 3196189429bc..5cd05d4fe1a9 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
>
>..snip..
>
>> @@ -1428,7 +1413,6 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
>>   	struct device_node *cec_np, *remote, *i2c_np;
>>   	struct platform_device *cec_pdev;
>>   	struct regmap *regmap;
>> -	struct resource *mem;
>>   	int ret;
>>
>>   	ret = mtk_hdmi_get_all_clk(hdmi, np);
>> @@ -1474,8 +1458,7 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
>>   	}
>>   	hdmi->sys_regmap = regmap;
>>
>> -	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> -	hdmi->regs = devm_ioremap_resource(dev, mem);
>> +	hdmi->regs = syscon_node_to_regmap(dev->of_node);
>
>Nack. You're breaking ABI, this will force everyone to add syscon to devicetree,
>hence this breaks retrocompatibility with old devicetrees.
>
>Hint: not here, device_node_to_regmap()

Hi Angelo,

I'm sorry, I didn't think device tree retro compatibility was a thing.

I'll drop the requirement for the module to be a syscon.
Thx for the hint.

Thx,
Guillaume.

>
>Regards,
>Angelo
>
>>   	if (IS_ERR(hdmi->regs)) {
>>   		ret = PTR_ERR(hdmi->regs);
>>   		goto put_device;
>
>