Re: [PATCH 1/2] dt-bindings: phy: qcom,sc8280xp-qmp-pcie-phy: Add vdda-refgen supply for Glymur

From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: Qiang Yu <qiang.yu@oss.qualcomm.com>,
	Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
	Vinod Koul <vkoul@kernel.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: phy: qcom,sc8280xp-qmp-pcie-phy: Add vdda-refgen supply for Glymur
Date: Tue, 3 Mar 2026 12:14:29 +0100	[thread overview]
Message-ID: <578c485e-b7d3-4468-bece-efeb6db2b1e1@oss.qualcomm.com> (raw)
In-Reply-To: <aaVkpKZcrNM7k4Xm@hu-qianyu-lv.qualcomm.com>

On 3/2/26 11:21 AM, Qiang Yu wrote:
> On Fri, Feb 13, 2026 at 07:47:36PM +0200, Dmitry Baryshkov wrote:
>> On Wed, Feb 11, 2026 at 07:32:23PM -0800, Qiang Yu wrote:
>>> On Mon, Feb 09, 2026 at 09:06:23AM +0100, Krzysztof Kozlowski wrote:
>>>> On Sun, Feb 08, 2026 at 08:49:39PM -0800, Qiang Yu wrote:
>>>>> The PCIe QMP PHYs on Glymur require stable reference voltage provided by
>>>>> refgen. The refgen itself requires two separate power supplies:
>>>>> vdda-refgen0p9 and vdda-refgen1p2.
>>>>>
>>>>> Since there is no dedicated driver for REFGEN, add vdda-refgen0p9-supply
>>>>
>>>> How does the driver matter for the bindings? If I add dedicated driver
>>>> for refgen, then I change the bindings?
>>>
>>> Yeah, I know that dt-bindings should describe hardware, not software. But
>>> what I meant to say is that the refgen is different from qref which is
>>> controlled via TCSR registers and its LDOs are requested to vote in
>>> tcsrcc driver. The refgen doesn't required register setting and it doesn't
>>> have dedicated driver, so we vote its LDOs in phy driver. I will avoid
>>> this statement in next version.
>>
>> I must admit, I could not find references to the refgen in any of Glymur
>> PCIe-related HPGs.
>>
>>>
>>>>
>>>> There is qcom,sc8280xp-refgen-regulator so why there cannot be
>>>> qcom,x1e-refgen-regulator?
>>>
>>> I think we can and it seems better because the refgen for pcie phy also
>>> supplies reference voltage to other modules like usb. But I checked the
>>> qcom-refgen-regulator.c, it contains some register settings and there is
>>> no LDOs voting. I'm not sure what does those register do, maybe Konrad
>>> can provide some backgroud.
>>
>> Those regs provide voting for refgen, because on those platforms DSI
>> block doesn't have a hardware vote for refgen.
> 
> Hi Konrad, Dmitry
> 
> I tried to model the reference voltage as a fixed regulator but the fixed
> regulator driver only supports a single vin-supply. However, the refgen
> block requires two separate power supplies (1.2V and 0.9V LDOs).
> 
> Would it be appropriate to modify the qcom-refgen-regulator.c driver to
> handle LDO voting for both the 1.2V and 0.9V supplies? In the regulator's
> enable/disable callbacks, we could vote for and unvote these two LDOs
> instead of performing register operations.

Wait, so you want to associate the MMIO-controlled refgen's driver with
a dummy regulator that takes 2 supplies? I didn't catch that part earlier,
that's not great..

Or do we actually have access to the MMIO of *this* refgen and can control
it (except we don't do that today because X Y Z)?

Konrad

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