Messages in this thread | | | Date | Wed, 15 Oct 2014 06:13:54 -0700 | From | Guenter Roeck <> | Subject | Re: [RFC PATCH v2 3/3] i2c: show and change bus frequency via sysfs |
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On 10/15/2014 04:49 AM, Octavian Purdila wrote: > On Tue, Oct 14, 2014 at 6:41 PM, Guenter Roeck <linux@roeck-us.net> wrote: >> >> On Tue, Oct 14, 2014 at 05:48:14PM +0300, Octavian Purdila wrote: >>> This patch adds three new sysfs files: bus_frequency, >>> bus_min_frequency and bus_max_frequency which allows the user to view >>> or change the bus frequency on a per bus level. >>> > > <snip> > >>> + >>> +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, >>> + i2c_sysfs_freq_store); >> >> Consider using DEVICE_ATTR_RO here. Also, extra empty line. >> > > Unfortunately that won't work because we must transform bus_frequency > to a RW entry (via is_visible) if the bus can change the frequency. We
Ah yes, you are right.
> can't use DEVIE_ATTR_RW either, because transforming a RW entry to a > RO entry with is visible is not possible: >
Why not ?
is_visible returns the desired mode. Just like you can return mode | S_IWUSR, you can return mode & ~S_IWUSR.
Am I missing something ?
Guenter
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