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

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Date:   Fri, 15 Mar 2019 05:58:18 -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 3/15/19 4:20 AM, John Garry wrote:
> On 14/03/2019 17:44, Guenter Roeck wrote:
>> On Thu, Mar 14, 2019 at 05:21:32PM +0000, John Garry wrote:
>>> On 14/03/2019 17:05, Guenter Roeck wrote:
>>>> 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");
>>>>
>>>
>>> Hi Guenter,
>>>
>>>> request_muxed_region() would be a better choice here since it doesn't
>>>> bail out immediately if the region is temporarily busy.
>>>
>>> Are you saying that this region could be busy due to another driver
>>> accessing this same region (probably for the same purpose)?
>>>
> 
> Hi Guenter,
> 
>> Depends on the definition of "same reason". To access the chip's
>> Super-IO configuration registers, yes, that can happen. I don't
>> see it used in the kernel today, but examples would be someone
>> adding support for the chips supported by this driver to gpio-f7188x,
>> or adding support for the F71872 watchdog to the f71808e_wdt driver.
> 
> OK, understood.
> 
> In terms of fixing these up, as mentioned @ https://www.spinics.net/lists/linux-pci/msg49843.html, there are other modules which have this issue. I asked Kefang today, and here's his list:
> 
> f71805f.ko
> f71882fg.ko
> pc87427.ko
> sch56xx-common.ko
> smsc47b397.ko
> smsc47m1.ko
> 
> So maybe it's better to send separate patch(sets) for 1/2 and 2/2+other hwmon fixes - let me know your preference.
> 

One patch per file, please.

Thanks,
Guenter

> Thanks,
> John
> 
>>
>> Guenter
>>
>> .
>>
> 
> 
>