Re: [PATCH 2/3] mailbox: renesas: Support MFIS mailbox driver

[Krzysztof Kozlowski <krzk@kernel.org>]

On 24/10/2025 08:22, Kuninori Morimoto wrote:
> From: Masashi Ozaki <masashi.ozaki.te@renesas.com>
> 
> Add Renesas MFIS mailbox driver for R8A78000 (X5H)
> 
> Signed-off-by: Masashi Ozaki <masashi.ozaki.te@renesas.com>
> Signed-off-by: Vinh Nguyen <vinh.nguyen.xz@renesas.com>
> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
> ---
>  drivers/mailbox/Kconfig             |  10 +-
>  drivers/mailbox/Makefile            |   2 +
>  drivers/mailbox/rcar-mfis-mailbox.c | 137 ++++++++++++++++++++++++++++
>  3 files changed, 148 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/mailbox/rcar-mfis-mailbox.c
> 
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index e47cb68989267..07e6bf06effe3 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -379,6 +379,15 @@ config BCM74110_MAILBOX
>  	  processor and coprocessor that handles various power management task
>  	  and more.
>  
> +config RCAR_MFIS_MBOX
> +	bool "Renesas R-Car Multifunctional Interface Mailbox Support"
> +	depends on ARM_SCMI_PROTOCOL && ARCH_RENESAS

I don't see any build restrictions, why no compile test?

> +	help
> +	  This driver provides support for SCMI interface transport with
> +	  MFIS(Multifunctional Interface).
> +	  It is used to send short message between CPU cores and
> +	  SCP(System Control Processor).
> +
>  config RISCV_SBI_MPXY_MBOX
>  	tristate "RISC-V SBI Message Proxy (MPXY) Mailbox"
>  	depends on RISCV_SBI
> @@ -389,5 +398,4 @@ config RISCV_SBI_MPXY_MBOX
>  	  remote processor through the SBI implementation (M-mode firmware
>  	  or HS-mode hypervisor). Say Y here if you want to have this support.
>  	  If unsure say N.
> -


Does not look as intended change.

...

> +
> +static int mfis_startup(struct mbox_chan *link)
> +{
> +	struct mbox_controller *mbox = link->mbox;
> +	struct device *dev = mbox->dev;
> +	int irq;
> +	int ret;
> +
> +	irq = of_irq_get(dev->of_node, 0);
> +
> +	ret = request_irq(irq, mfis_rx_interrupt,
> +			  IRQF_SHARED, "mfis-mbox", link);
> +	if (ret) {
> +		dev_err(dev,
> +			"Unable to acquire IRQ %d\n", irq);

Please don't wrap lines when not necessary. This only hurts readability.


> +		return ret;
> +	}



> +
> +	ret = mbox_controller_register(mbox);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, mbox);
> +	dev_info(dev, "MFIS mailbox is probed\n");


This does not look like useful printk message. Drivers should be silent
on success:
https://elixir.bootlin.com/linux/v6.15-rc7/source/Documentation/process/coding-style.rst#L913
https://elixir.bootlin.com/linux/v6.15-rc7/source/Documentation/process/debugging/driver_development_debugging_guide.rst#L79

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id mfis_mbox_of_match[] = {
> +	{ .compatible = "renesas,mfis-mbox", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, mfis_mbox_of_match);
> +
> +static struct platform_driver mfis_mbox_driver = {
> +	.driver = {
> +		.name = "renesas-mfis-mbox",
> +		.of_match_table = mfis_mbox_of_match,
> +	},
> +	.probe	= mfis_mbox_probe,
> +};
> +module_platform_driver(mfis_mbox_driver);
> +MODULE_DESCRIPTION("Renesas MFIS mailbox driver");
> +MODULE_LICENSE("GPL v2");


Best regards,
Krzysztof