Re: [PATCH v7 10/23] scsi: ufs: mediatek: Handle misc host voltage regulators

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
To: "Peter Wang (王信友)" <peter.wang@mediatek.com>,
	"chu.stanley@gmail.com" <chu.stanley@gmail.com>,
	"robh@kernel.org" <robh@kernel.org>,
	"Chunfeng Yun (云春峰)" <Chunfeng.Yun@mediatek.com>,
	"kishon@kernel.org" <kishon@kernel.org>,
	"James.Bottomley@HansenPartnership.com"
	<James.Bottomley@HansenPartnership.com>,
	"bvanassche@acm.org" <bvanassche@acm.org>,
	"neil.armstrong@linaro.org" <neil.armstrong@linaro.org>,
	"conor+dt@kernel.org" <conor+dt@kernel.org>,
	"Chaotian Jing (井朝天)" <Chaotian.Jing@mediatek.com>,
	"lgirdwood@gmail.com" <lgirdwood@gmail.com>,
	"nicolas.frattaroli@collabora.com"
	<nicolas.frattaroli@collabora.com>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"krzk+dt@kernel.org" <krzk+dt@kernel.org>,
	"p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
	"alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"avri.altman@wdc.com" <avri.altman@wdc.com>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"broonie@kernel.org" <broonie@kernel.org>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-phy@lists.infradead.org" <linux-phy@lists.infradead.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>,
	"kernel@collabora.com" <kernel@collabora.com>
Subject: Re: [PATCH v7 10/23] scsi: ufs: mediatek: Handle misc host voltage regulators
Date: Tue, 24 Feb 2026 13:41:50 +0100	[thread overview]
Message-ID: <24445e6d-c308-4df2-8b3e-7ee8a8e3f2fe@collabora.com> (raw)
In-Reply-To: <2c7c84a2df19624ba9f207fd3fee47a8bdd9d8dc.camel@mediatek.com>

Il 24/02/26 13:38, Peter Wang (王信友) ha scritto:
> On Mon, 2026-02-16 at 14:37 +0100, Nicolas Frattaroli wrote:
>> @@ -1188,8 +1190,21 @@ static int ufs_mtk_get_supplies(struct
>> ufs_mtk_host *host)
>>   {
>>   	struct device *dev = host->hba->dev;
>>   	const struct ufs_mtk_soc_data *data =
>> of_device_get_match_data(dev);
>> +	int ret;
>> +
>> +	if (!data)
>> +		return 0;
>> +
>> +	if (data->num_reg_names) {
>> +		ret = devm_regulator_bulk_get_enable(dev, data-
>>> num_reg_names,
>> +						     data-
>>> reg_names);
> 
> Hi Nicolas,
> 
> If these regulators are only acquired and enabled once,
> why not just set regulator-always-on in the device tree?
> 

Because:
  1. The UFS driver has to acquire the correct supplies regardless of them
     being on, guaranteeing both a readable power tree (sysfs/debugfs) and
     a correct hardware description in devicetree.
  2. A future update might get those regulators disabled during deep sleep

Regards,
Angelo

> Thanks
> Peter
> 


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