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Message-ID: <20251105033817.20427-1-Niklaus.Liu@mediatek.com>
Date: Wed, 5 Nov 2025 11:38:02 +0800
From: niklaus.liu <Niklaus.Liu@...iatek.com>
To: Matthias Brugger <matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>
CC: <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-mediatek@...ts.infradead.org>,
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	<sirius.wang@...iatek.com>, <vince-wl.liu@...iatek.com>,
	<jh.hsu@...iatek.com>, <zhigang.qin@...iatek.com>, <sen.chu@...iatek.com>,
	Niklaus Liu <niklaus.liu@...iatek.com>, niklaus.liu
	<Niklaus.Liu@...iatek.com>
Subject:

Refer to the discussion in the link:
v3: https://patchwork.kernel.org/project/linux-mediatek/patch/20251104071252.12539-2-Niklaus.Liu@mediatek.com/

Subject: [PATCH v4 0/1] soc: mediatek: mtk-regulator-coupler: Add support for MT8189

changes in v4:
 - reply comment:
1. MTK hardware requires that vsram_gpu must be higher than vgpu; this rule must be satisfied.

2. When the GPU powers on, the mtcmos driver first calls regulator_enable to turn on vgpu, then calls regulator_enable to 
turn on vsram_gpu. When enabling vgpu, mediatek_regulator_balance_voltage sets the voltages for both vgpu and vsram_gpu. 
However, when enabling vsram_gpu, mediatek_regulator_balance_voltage is also executed, and at this time, the vsram_gpu voltage 
is set to the minimum voltage specified in the DTS, which does not comply with the requirement that vsram_gpu must be higher than vgpu.

3.During suspend, the voltages of vgpu and vsram_gpu should remain unchanged, and when resuming, vgpu and vsram_gpu should be 
restored to their previous voltages. When the vgpu voltage is adjusted, mediatek_regulator_balance_voltage already synchronizes the 
adjustment of vsram_gpu voltage. Therefore, adjusting the vsram_gpu voltage again in mediatek_regulator_balance_voltage is redundant. 

changes in v3:
 - modify for comment[add the new entry by alphabetical order]

changes in v2:
 - change title for patch
 - reply comment: This is a software regulator coupler mechanism, and the regulator-coupled-with
configuration has been added in the MT8189 device tree. This patchaddresses an issue reported by a
Chromebook customer. When the GPU regulator is turned on, mediatek_regulator_balance_voltage already
sets both the GPU and GPU_SRAM voltages at the same time, so there is no need to adjust the GPU_SRAM
voltage again in a second round. Therefore, a return is set for MT8189.
If the user calls mediatek_regulator_balance_voltage again for GPU_SRAM, it may cause abnormal behavior of GPU_SRAM.

changes in v1:
 - mediatek-regulator-coupler mechanism for platform MT8189

*** BLURB HERE ***

Niklaus Liu (1):
  soc: mediatek: mtk-regulator-coupler: Add support for MT8189

 drivers/soc/mediatek/mtk-regulator-coupler.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

-- 
2.46.0