linux-kernel - Re: [PATCH v3 6/6] PCI: pwrctl: Add power control driver for qps615

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Message-ID: <CAMRc=McOaiLEfum0L1iEk8HzjXVjvjCqRq=29b_Mphdwi_cZEg@mail.gmail.com>
Date: Wed, 13 Nov 2024 14:38:55 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>
Cc: andersson@...nel.org, Bjorn Helgaas <bhelgaas@...gle.com>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kw@...ux.com>, 
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, cros-qcom-dts-watchers@...omium.org, 
	Jingoo Han <jingoohan1@...il.com>, quic_vbadigan@...cinc.com, 
	linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 6/6] PCI: pwrctl: Add power control driver for qps615

On Tue, Nov 12, 2024 at 4:02 PM Krishna chaitanya chundru
<quic_krichai@...cinc.com> wrote:
>
> QPS615 is the PCIe switch which has one upstream and three downstream
> ports. To one of the downstream ports ethernet MAC is connected as endpoint
> device. Other two downstream ports are supposed to connect to external
> device. One Host can connect to QPS615 by upstream port. QPS615 switch
> needs to be configured after powering on and before PCIe link was up.
>
> The PCIe controller driver already enables link training at the host side
> even before qps615 driver probe happens, due to this when driver enables
> power to the switch it participates in the link training and PCIe link
> may come up before configuring the switch through i2c. To prevent the
> host from participating in link training, disable link training on the
> host side to ensure the link does not come up before the switch is
> configured via I2C.
>
> Based up on dt property and type of the port, qps615 is configured
> through i2c.
>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---

Krishna,

This looks really good thanks.

One nit: I'd rename qps615_pwrctl_power_on() to something else as most
of its code does configure the switch, not power it up. Maybe
qps615_pwrctl_bring_up()?

With that and the build issue fixed:

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

I'll test it once it compiles.

Bart