linux-kernel - Re: [RFC PATCH 2/2] hwmon: (f71805f): Use request_region() in f71805f

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Date:   Thu, 14 Mar 2019 10:05:34 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     John Garry <john.garry@...wei.com>
Cc:     jdelvare@...e.com, bhelgaas@...gle.com, rafael@...nel.org,
        arnd@...db.de, lorenzo.pieralisi@....com, bp@...e.de,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, wangkefeng.wang@...wei.com,
        linuxarm@...wei.com
Subject: Re: [RFC PATCH 2/2] hwmon: (f71805f): Use request_region() in
 f71805f_init()

On Fri, Mar 15, 2019 at 12:55:16AM +0800, John Garry wrote:
> Currently the driver does not call request_region() prior to
> accessing IO port regions in f71805f_init(), so add it.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>  drivers/hwmon/f71805f.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/hwmon/f71805f.c b/drivers/hwmon/f71805f.c
> index 73c681162653..910082c7f184 100644
> --- a/drivers/hwmon/f71805f.c
> +++ b/drivers/hwmon/f71805f.c
> @@ -1617,10 +1617,21 @@ static int __init f71805f_init(void)
>  	int err;
>  	unsigned short address;
>  	struct f71805f_sio_data sio_data;
> +	struct resource *res;
> +	size_t size = 0x4e - 0x2e + SIO_REG_ADDR + 4;
> +
> +	/* Request the whole 0x2e - 0x4e region */
> +	res = request_region(0x2e, size, "f71805f");

request_muxed_region() would be a better choice here since it doesn't
bail out immediately if the region is temporarily busy.

Thanks,
Guenter

> +	if (!res)
> +		return -EBUSY;
>  
>  	if (f71805f_find(0x2e, &address, &sio_data)
> -	 && f71805f_find(0x4e, &address, &sio_data))
> +	 && f71805f_find(0x4e, &address, &sio_data)) {
> +		release_region(0x2e, size);
>  		return -ENODEV;
> +	}
> +
> +	release_region(0x2e, size);
>  
>  	err = platform_driver_register(&f71805f_driver);
>  	if (err)
> -- 
> 2.17.1
>