linux-kernel - Re: [PATCH v5 8/9] PCI: pwrctrl: Add power control driver for tc9563

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Message-ID: <lc4kdlyxizslok5dhesv5midbgrmvrke54auklabtlzb33hiqx@u2racokpm7zm>
Date: Fri, 27 Jun 2025 15:17:45 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: 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>,
        chaitanya chundru <quic_krichai@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        cros-qcom-dts-watchers@...omium.org, Jingoo Han <jingoohan1@...il.com>,
        Bartosz Golaszewski <brgl@...ev.pl>, quic_vbadigan@...cnic.com,
        amitk@...nel.org, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, jorge.ramirez@....qualcomm.com,
        Dmitry Baryshkov <lumag@...nel.org>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v5 8/9] PCI: pwrctrl: Add power control driver for tc9563

On Sat, Apr 12, 2025 at 07:19:57AM +0530, Krishna Chaitanya Chundru wrote:
> TC9563 is a 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 TC9563 by upstream port. TC9563 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 this 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. Once the link is
> up the configuration done through i2c will not have any affect.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, tc9563 is configured
> through i2c.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
> Reviewed-by: Bjorn Andersson <andersson@...nel.org>
> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
>  drivers/pci/pwrctrl/Kconfig              |  10 +
>  drivers/pci/pwrctrl/Makefile             |   2 +
>  drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c | 628 +++++++++++++++++++++++++++++++
>  3 files changed, 640 insertions(+)
> 
> diff --git a/drivers/pci/pwrctrl/Kconfig b/drivers/pci/pwrctrl/Kconfig
> index 990cab67d41332a8508d4150825c621eb86322c5..d14ef2b0ffd84f9a8c4266fdd57a27f7f3611ca4 100644
> --- a/drivers/pci/pwrctrl/Kconfig
> +++ b/drivers/pci/pwrctrl/Kconfig
> @@ -21,3 +21,13 @@ config PCI_PWRCTL_SLOT
>  	  This is a generic driver that controls the power state of different
>  	  PCI slots. The voltage regulators powering the rails of the PCI slots
>  	  are expected to be defined in the devicetree node of the PCI bridge.
> +
> +config PCI_PWRCTRL_TC9563
> +	tristate "PCI Power Control driver for TC9563 PCIe switch"
> +	select PCI_PWRCTL
> +	help
> +	  Say Y here to enable the PCI Power Control driver of TC9563 PCIe
> +	  switch.
> +
> +	  This driver enables power and configures the TC9563 PCIe switch
> +	  through i2c.
> diff --git a/drivers/pci/pwrctrl/Makefile b/drivers/pci/pwrctrl/Makefile
> index ddfb12c5aadf684cf675585b1078ecb7c24649cc..5d0163c75878d5bf702bc6c892fa31bfea5a95e3 100644
> --- a/drivers/pci/pwrctrl/Makefile
> +++ b/drivers/pci/pwrctrl/Makefile
> @@ -7,3 +7,5 @@ obj-$(CONFIG_PCI_PWRCTL_PWRSEQ)		+= pci-pwrctrl-pwrseq.o
>  
>  obj-$(CONFIG_PCI_PWRCTL_SLOT)		+= pci-pwrctl-slot.o
>  pci-pwrctl-slot-y			:= slot.o
> +
> +obj-$(CONFIG_PCI_PWRCTRL_TC9563)	+= pci-pwrctrl-tc9563.o
> diff --git a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..547c764a6f405a676216309ef6ebcaffbbc3f1d6
> --- /dev/null
> +++ b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
> @@ -0,0 +1,628 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>

Missing #include <linux/gpiod/consumer.h>

You are using gpiod_*() calls, but don't include a corresponding header,
which breaks your driver on arm platform.

> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/pci.h>
> +#include <linux/pci-pwrctrl.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +#include <linux/unaligned.h>
> +

-- 
With best wishes
Dmitry