linux-kernel - Re: [PATCH v3 5/5] phy: qcom: qmp-pcie: add x1e80100 qref supplies

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Message-ID: <aBx9LB_qQIvA0bj8@hovoldconsulting.com>
Date: Thu, 8 May 2025 11:45:16 +0200
From: Johan Hovold <johan@...nel.org>
To: Qiang Yu <quic_qianyu@...cinc.com>
Cc: Wenbin Yao <quic_wenbyao@...cinc.com>, catalin.marinas@....com,
	will@...nel.org, linux-arm-kernel@...ts.infradead.org,
	andersson@...nel.org, konradybcio@...nel.org, robh@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org,
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, vkoul@...nel.org, kishon@...nel.org,
	sfr@...b.auug.org.au, linux-phy@...ts.infradead.org,
	krishna.chundru@....qualcomm.com, quic_vbadigan@...cinc.com,
	quic_mrana@...cinc.com, quic_cang@...cinc.com,
	Johan Hovold <johan+linaro@...nel.org>,
	Abel Vesa <abel.vesa@...aro.org>
Subject: Re: [PATCH v3 5/5] phy: qcom: qmp-pcie: add x1e80100 qref supplies

On Thu, May 08, 2025 at 04:50:30PM +0800, Qiang Yu wrote:
> 
> On 5/8/2025 4:20 PM, Johan Hovold wrote:
> > On Thu, May 08, 2025 at 04:15:14PM +0800, Wenbin Yao wrote:
> >> From: Qiang Yu <quic_qianyu@...cinc.com>
> >>
> >> All PCIe PHYs on the X1E80100 SOC require the vdda-qref, which feeds QREF
> >> clocks provided by the TCSR device.
> > This still looks wrong and you never replied to why these supplies
> > shouldn't be handled by the tcsr clock driver that supplies these
> > clocks:
> >
> > 	https://lore.kernel.org/lkml/aBHUmXx6N72_sCH9@hovoldconsulting.com/

> Sorry, I thought Konrad had convinced you.

IIRC, he just said you guys were told to add the QREF supply to the PHY.
That's not an argument.

> If the TCSR driver manages these supplies, would it be possible for tscr
> driver to recognize when it needs to turn vdda-qref on or off for a
> specific PCIe port?

Sure, just add a lookup table to the driver and enable the required
supplies when a ref clock is enabled.

As I mentioned in the other thread, the T14s has the following QREF
supplies:

	
	VDD_A_QREFS_1P2_A
	VDD_A_QREFS_1P2_B

	VDD_A_QREFS_0P875_A
	VDD_A_QREFS_0P875_B
	VDD_A_QREFS_0P875_0
	VDD_A_QREFS_0P875_2
	VDD_A_QREFS_0P875_3

and it's not clear how these maps to the various consumer ref clocks,
including the PCIe ones:

	#define TCSR_PCIE_2L_4_CLKREF_EN
	#define TCSR_PCIE_2L_5_CLKREF_EN
	#define TCSR_PCIE_8L_CLKREF_EN
	#define TCSR_PCIE_4L_CLKREF_EN

That mapping can be done by the TCSR clock driver (which would also take
care of the 1.2 V supplies).

Johan