linux-kernel - Re: [PATCH v7 08/11] misc: rp1: RaspberryPi RP1 misc driver

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Message-ID: <20250314083730.GC234496@rocinante>
Date: Fri, 14 Mar 2025 17:37:30 +0900
From: Krzysztof Wilczynski <kw@...ux.com>
To: Andrea della Porta <andrea.porta@...e.com>
Cc: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Bartosz Golaszewski <brgl@...ev.pl>,
	Derek Kiernan <derek.kiernan@....com>,
	Dragan Cvetic <dragan.cvetic@....com>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Saravana Kannan <saravanak@...gle.com>, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-gpio@...r.kernel.org,
	Masahiro Yamada <masahiroy@...nel.org>,
	Stefan Wahren <wahrenst@....net>,
	Herve Codina <herve.codina@...tlin.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v7 08/11] misc: rp1: RaspberryPi RP1 misc driver

Hello,

Even though this is not for the PCI sub-system directly, I had a very brief
look over the code.  I hope you don't mind.

As such, a few nit picks, nothing blocking.

> +# RaspberryPi RP1 misc device

Would this be better if it matched the "tristate" description below?

> +config MISC_RP1
> +	tristate "RaspberryPi RP1 PCIe support"
> +	depends on OF_IRQ && OF_OVERLAY && PCI_MSI && PCI_QUIRKS
> +	select PCI_DYNAMIC_OF_NODES
> +	help
> +	  Support the RP1 peripheral chip found on Raspberry Pi 5 board.
> +
> +	  This device supports several sub-devices including e.g. Ethernet
> +	  controller, USB controller, I2C, SPI and UART.
> +
> +	  The driver is responsible for enabling the DT node once the PCIe
> +	  endpoint has been configured, and handling interrupts.
> +
> +	  This driver uses an overlay to load other drivers to support for
> +	  RP1 internal sub-devices.

> +/* the dts overlay is included from the dts directory so

  /*
   * The dts overlay is included from the dts directory so

To make the code comment match rest of the style.

> +/*
> + * Copyright (c) 2018-24 Raspberry Pi Ltd.
> + * All rights reserved.

  Copyright (c) 2018-2025 Raspberry Pi Ltd.

To spell the current year fully, plus update it to 2025 already.

I would also add an extra newline here to split the two apart a bit.

> +	if (pci_resource_len(pdev, 1) <= 0x10000) {
> +		dev_err(&pdev->dev,
> +			"Not initialised - is the firmware running?\n");
> +		return -EINVAL;
> +	}

The American spelling in the above might be better.  But I don't have
strong opinions here.  It seems more popular in error messages.

> +	err = pci_alloc_irq_vectors(pdev, RP1_INT_END, RP1_INT_END,
> +				    PCI_IRQ_MSIX);
> +	if (err < 0) {
> +		return dev_err_probe(&pdev->dev, err,
> +				     "pci_alloc_irq_vectors failed");

Missing a new line at the end, but also...

  return dev_err_probe(&pdev->dev, err,
		       "Failed to allocate MSI-X vectors\n");

Or, something like this over this the function name.  Perhaps exposing
error code could be useful to the end user? If so then something like this:

  return dev_err_probe(&pdev->dev, err,
		       "Failed to allocate MSI-X vectors, err=%d\n", err);

Here and other errors where appropriate.

> +	for (i = 0; i < RP1_INT_END; i++) {
> +		unsigned int irq = irq_create_mapping(rp1->domain, i);
> +
> +		if (!irq) {
> +			dev_err(&pdev->dev, "failed to create irq mapping\n");

  dev_err(&pdev->dev, "Failed to create IRQ mapping\n");

To make the error message capitalisation consistent.

> +static const struct pci_device_id dev_id_table[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_RPI, PCI_DEVICE_ID_RPI_RP1_C0), },
> +	{ 0, }

  { }

Would probably be sufficient.

> +MODULE_AUTHOR("Phil Elwell <phil@...pberrypi.com>");
> +MODULE_AUTHOR("Andrea della Porta <andrea.porta@...e.com>");
> +MODULE_DESCRIPTION("RP1 wrapper");

  RaspberryPi RP1 misc device

To match the Kconfig comment in the above description or the one from the
"tristate" also in Kconfig.

Thank you for all the work here!

	Krzysztof