Re: [PATCH] i2c: piix4: Fix request_region size

From	Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] i2c: piix4: Fix request_region size
Date	2017-01-30 02:20 +0100
Message-ID	<t58Ns-64o-11@gated-at.bofh.it> (permalink)
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Hi Jean and Wolfram

On Sat, Jan 28, 2017 at 12:13 PM, Jean Delvare <jdelvare@suse.de> wrote:
> Hi Wolfram,
>
> On Sat, 28 Jan 2017 12:00:21 +0100, Wolfram Sang wrote:
>>
>> > >  /* count for request_region */
>> > > -#define SMBIOSIZE        8
>> > > +#define SMBIOSIZE        9
>> >
>> > Are you certain that all supported devices have this extra register?
>>
>> Isn't it better to have a potentially unused register mapped than a
>> potentially used register unmapped

We have been  "lucky" that it is a ioport and not a mmap region,
otherwise we would have seen a nice oops :).

>
> My concern is that the region request could fail due to a conflict with
> another device, if the physical I/O region is only 8 and we try to
> request 9.

I do not think that this is the case, if you check the top of the file
you can see how there are many other definitions for registers. I
expect that SMBIOSIZE=8 is just the original author being
conservative.

Of course I cannot say that there is one platform where one extra
ioport can cause a conflict, but I believe that we must request all
the ports that we will use.

Regards!
>
> --
> Jean Delvare
> SUSE L3 Support

-- 
Ricardo Ribalda

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[PATCH] i2c: piix4: Fix request_region size Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com> - 2017-01-27 16:20 +0100
  Re: [PATCH] i2c: piix4: Fix request_region size Jean Delvare <jdelvare@suse.de> - 2017-01-28 09:40 +0100
    Re: [PATCH] i2c: piix4: Fix request_region size Wolfram Sang <wsa@the-dreams.de> - 2017-01-28 12:10 +0100
      Re: [PATCH] i2c: piix4: Fix request_region size Jean Delvare <jdelvare@suse.de> - 2017-01-28 12:20 +0100
        Re: [PATCH] i2c: piix4: Fix request_region size Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com> - 2017-01-30 02:20 +0100

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