linux-kernel - Re: [PATCH] mailbox: qcom: Support building QCOM IPCC driver as module

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Date:   Wed, 21 Oct 2020 11:29:55 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Huang Yiwei <hyiwei@...eaurora.org>
Cc:     jassisinghbrar@...il.com, agross@...nel.org,
        bjorn.andersson@...aro.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] mailbox: qcom: Support building QCOM IPCC driver as
 module

Hi,

Please CC the driver maintainer(s) for relevant patches. For this driver,
I've been listed as the maintainer in the MAINTAINERS file.

On Wed, Oct 21, 2020 at 10:15:52AM +0800, Huang Yiwei wrote:
> Change CONFIG_QCOM_IPCC to tristate and add exit function to
> support module build for QCOM IPCC driver.
> 

This is not going to work, sorry! There was a reason to make this driver
built-in in the first place. This driver registers itself as an irqchip and
provides interrupts to be consumed by the client drivers. So if we want to
unload the driver, then we should make sure to dispose all irqs consumed by
the client drivers and that's not possible currently. If you look into other
irqchip drivers, they're all made as built-in.

Thanks,
Mani

> Signed-off-by: Huang Yiwei <hyiwei@...eaurora.org>
> ---
>  drivers/mailbox/Kconfig     | 2 +-
>  drivers/mailbox/qcom-ipcc.c | 6 ++++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 05b1009..78f3006 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -245,7 +245,7 @@ config SPRD_MBOX
>  	  you want to build the Spreatrum mailbox controller driver.
>  
>  config QCOM_IPCC
> -	bool "Qualcomm Technologies, Inc. IPCC driver"
> +	tristate "Qualcomm Technologies, Inc. IPCC driver"
>  	depends on ARCH_QCOM || COMPILE_TEST
>  	help
>  	  Qualcomm Technologies, Inc. Inter-Processor Communication Controller
> diff --git a/drivers/mailbox/qcom-ipcc.c b/drivers/mailbox/qcom-ipcc.c
> index 2d13c72..1ed9a87 100644
> --- a/drivers/mailbox/qcom-ipcc.c
> +++ b/drivers/mailbox/qcom-ipcc.c
> @@ -280,6 +280,12 @@ static int __init qcom_ipcc_init(void)
>  }
>  arch_initcall(qcom_ipcc_init);
>  
> +static __exit void qcom_ipcc_exit(void)
> +{
> +	platform_driver_unregister(&qcom_ipcc_driver);
> +}
> +module_exit(qcom_ipcc_exit);
> +
>  MODULE_AUTHOR("Venkata Narendra Kumar Gutta <vnkgutta@...eaurora.org>");
>  MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>");
>  MODULE_DESCRIPTION("Qualcomm Technologies, Inc. IPCC driver");
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>