Re: [PATCH] misc,acpi,backlight: MSI S270 Laptop support

Dmitry Torokhov
2006-10-04T01:37:33Z

On Tuesday 03 October 2006 21:28, Lennart Poettering wrote:
> On Mon, 02.10.06 22:27, Dmitry Torokhov (dtor@insightbb.com) wrote:
>
> > > + ret = sysfs_create_group(&msipf_device->dev.kobj, &msipf_attribute_group);
> > > + if (ret)
> > > + goto fail_platform_device;
> > > +
> > > +
> > > + /* Enable automatic brightness control again */
> > > + if (auto_brightness != 2)
> > > + set_auto_brightness(1);
> > > +
> >
> > What happens if auto_brightness is 2 but userspace messed up with it
> > through device's sysfs attribute?
>
> If auto_brightness is 2 we assume that the user doesn't want the
> module to fiddle with the automatic brightness control
> automatically. So we don't do it, neither when loading nor when
> unloading the module. However, if the user wants to fiddle with the
> setting through sysfs he may do so and we will not reset his changes
> when unloading the module. This allows the user to do something like
> this to disable the brightness control without having the the driver
> loaded the whole time:
>
> modprobe msi-laptop auto_brightness=2 && echo 0 > /sys/devices/platform/msi-laptop-pf/auto_brightness && modprobe -r msi-laptop
>
> If auto_brightness is 1 or 0, we do as requested but reset the control
> to the bootup default when unloading. (i.e. enable it again)

Normally drivers clean up after themselves as if they were never loaded,
taht is why I questioned partial cleanup.

--
Dmitry