Messages in this thread | | | Date | Thu, 11 Sep 2014 13:21:34 +0200 | From | Thierry Reding <> | Subject | Re: [PATCH RFC 3/4] backlight: add kernel-internal backlight API |
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On Thu, Sep 11, 2014 at 01:14:31PM +0200, David Herrmann wrote: > Hi > > On Thu, Sep 11, 2014 at 1:10 PM, Thierry Reding > <thierry.reding@gmail.com> wrote: > > On Wed, Sep 10, 2014 at 05:54:22PM +0200, David Herrmann wrote: > > [...] > >> +void backlight_set_brightness(struct backlight_device *bd, unsigned int value, > >> + enum backlight_update_reason reason) > >> +{ > >> + mutex_lock(&bd->ops_lock); > >> + if (bd->ops) { > >> + value = clamp(value, 0U, (unsigned)bd->props.max_brightness); > > > > max_brightness should really be unsigned to begin with... > > > >> + pr_debug("set brightness to %u\n", value); > > > > dev_dbg(&bd->dev, ...)? > > I agree with both comments, but I tried to be consistent with what > brightness_store() does.
Fair enough, this can be cleaned up in separate patches.
> >> diff --git a/include/linux/backlight.h b/include/linux/backlight.h > >> index adb14a8..bcc0dec 100644 > >> --- a/include/linux/backlight.h > >> +++ b/include/linux/backlight.h > >> @@ -141,6 +141,22 @@ extern bool backlight_device_registered(enum backlight_type type); > >> extern int backlight_register_notifier(struct notifier_block *nb); > >> extern int backlight_unregister_notifier(struct notifier_block *nb); > >> > >> +struct backlight_device *backlight_device_lookup(const char *name); > >> +void backlight_set_brightness(struct backlight_device *bd, unsigned int value, > >> + enum backlight_update_reason reason); > >> + > >> +static inline void backlight_device_ref(struct backlight_device *bd) > >> +{ > >> + if (bd) > >> + get_device(&bd->dev); > >> +} > > > > Perhaps for consistency with get_device() this should return bd? That > > way you can chain things like so: > > > > priv->backlight = backlight_device_ref(bd); > > Makes sense, will change it. Same is actually true for _unref(), which > should return NULL unconditionally. This way, you can use: > priv->backlight = backlight_device_unref(priv->backlight); > to release a reference and reset the pointer at the same time.
That looks somewhat odd to me. Wouldn't priv->backlight typically go away after the unref anyway (presumably because priv is going to get freed soon after)?
But I have no strong objections to returning NULL from _unref(), if code doesn't need it it can always choose not to use the return value.
Thierry [unhandled content-type:application/pgp-signature] | |