Re: [RFC PATCH 2/2] hwmon: (f71805f): Use request_region() in f71805f_init()

[John Garry]

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@xxxxxxxxxx>
> > > > ---
> > > > 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.

Thanks,
John

> Guenter
>
> .