Re: [PATCH v1 1/1] drm/mediatek/dp: The register is written with the parsed DTS SSC value.

From: Krzysztof Kozlowski <krzk@kernel.org>
To: Liankun Yang <liankun.yang@mediatek.com>,
	chunkuang.hu@kernel.org, p.zabel@pengutronix.de,
	chunfeng.yun@mediatek.com, vkoul@kernel.org, kishon@kernel.org,
	matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com,
	jitao.shi@mediatek.com, mac.shen@mediatek.com
Cc: dri-devel@lists.freedesktop.org,
	linux-mediatek@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-phy@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/1] drm/mediatek/dp: The register is written with the parsed DTS SSC value.
Date: Wed, 3 Apr 2024 16:56:24 +0200	[thread overview]
Message-ID: <86dd866a-8ead-4fd1-993a-672d4947ba84@kernel.org> (raw)
In-Reply-To: <c0986506-ba8b-4c52-88f8-119c23b8778c@kernel.org>

On 03/04/2024 08:41, Krzysztof Kozlowski wrote:
> On 03/04/2024 06:05, Liankun Yang wrote:
>> [Description]
>> Severe screen flickering has been observed on the external display
>> when the DP projection function is used with the market expansion dock.
>>
> 
>> +	if (!strcmp(mode_name, RG_XTP_GLB_TXPLL_SSC_DELTA_RBR)) {
>> +		regmap_update_bits(dp_phy->regs, ssc_reg_offset,
>> +			   XTP_GLB_TXPLL_SSC_DELTA_RBR_DEFAULT, read_value);
>> +	} else if (!strcmp(mode_name, RG_XTP_GLB_TXPLL_SSC_DELTA_HBR)) {
>> +		read_value = read_value << 16 | 0x0000;
>> +		regmap_update_bits(dp_phy->regs, ssc_reg_offset,
>> +			   XTP_GLB_TXPLL_SSC_DELTA_HBR_DEFAULT, read_value);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct device_node *mtk_dp_get_ssc_node(struct phy *phy, struct mtk_dp_phy *dp_phy)
>> +{
>> +	struct device_node *mode_node = NULL;
>> +
>> +	mode_node = of_find_node_by_name(dp_phy->dev->of_node, SSC_SETTING);
> 
> ?!?!
> You have the node, why do you try to find it?
> 

Wait, that was brainfuck from my side or -ENOCOFFEE. Ignore.

I still have a question though, where did you document new ABI:
dependency on the node name here?

Also, why you are not going through direct children -
of_get_child_by_name()?

Best regards,
Krzysztof

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