Messages in this thread | | | Date | Wed, 29 Feb 2012 10:26:28 +0800 | From | Dong Aisheng <> | Subject | Re: [PATCH 19/20] pinctrl: API changes to support multiple states per device |
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On Tue, Feb 28, 2012 at 09:04:10AM -0800, Stephen Warren wrote: > Dong Aisheng wrote at Monday, February 27, 2012 8:19 PM: > > On Mon, Feb 27, 2012 at 10:37:16AM -0800, Stephen Warren wrote: > > > Dong Aisheng wrote at Monday, February 27, 2012 2:07 AM: > > > > On Sun, Feb 19, 2012 at 11:45:59PM -0700, Stephen Warren wrote: > > .......... > > > > > > > > +static struct pinctrl *pinctrl_get_locked(struct device *dev) > > > > > +{ > > > > > + struct pinctrl *p; > > > > > > > > > > -error: > > > > > - list_for_each_entry(setting, &p->settings, node) > > > > > - pinmux_free_setting(setting); > > > > > + if (WARN_ON(!dev)) > > > > > + return ERR_PTR(-EINVAL); > > > > > > > > > > - kfree(p); > > > > > + p = find_pinctrl(dev); > > > > > + if (p == NULL) > > > > > + p = create_pinctrl(dev); > > > > > + if (IS_ERR(p)) > > > > > + return p; > > > > > + > > > > > + p->usecount++; > > > > > > > > I still can not understand what's the purpose of p->usecount? > > > > For allowing multi times calling of pinctrl_get for on the same device? > > > > > > pinctrl_get() could be called multiple times for the same device. Rather > > > than create a whole new struct pinctrl each time it's called, we just > > > reference count the object so that each call returns the same one, and > > > it won't be destroyed until all users have called pinctrl_put(). > ... > > I still can't find in which case the device will have such requirement > > since per my understanding pinctrl is a little different from clock > > (clock can be used by different devices but we do not allow pins to be > > used by difference devices at the same time). > > True. It's actually very easy to make pinctrl_get() fail if a struct > pinctrl was already created for the device in question. If we do that, > we can completely remove the usecount field. I'll update my patch to do > that. Great.
> > > > > > +static inline struct pinctrl * __must_check pinctrl_get_select( > > > > > + struct device *dev, const char *name) > > > > > +{ > > > > > + struct pinctrl *p; > > > > > + struct pinctrl_state *s; > > > > > + int ret; > > > > > + > > > > > + p = pinctrl_get(dev); > > > > > + if (IS_ERR(p)) > > > > > + return p; > > > > > + > > > > > + s = pinctrl_lookup_state(p, name); > > > > > + if (IS_ERR(s)) { > > > > > + pinctrl_put(p); > > > > > + return ERR_PTR(PTR_ERR(s)); > > > > > + } > > > > > + > > > > > + ret = pinctrl_select_state(p, s); > > > > > + if (ret < 0) { > > > > > + pinctrl_put(p); > > > > > + return ERR_PTR(ret); > > > > > > > > s/ERR_PTR(ret)/ret ? > > > > > > The function returns a pointer, whereas ret is an int. ERR_PTR() is used > > > to wrap the int error code into a pointer value so that the function can > > > return either a valid pointer, or an error-code. See include/linux/err.h. > > > > Hmm, below is what i see in your patch: > > +int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state) > > { > > + int ret; > > + > > mutex_lock(&pinctrl_mutex); > > - pinctrl_disable_locked(p); > > + ret = pinctrl_select_state_locked(p, state); > > mutex_unlock(&pinctrl_mutex); > > + > > + return ret; > > } > > > > It seems pinctrl_select_state does not return a pointer. > > pinctrl_select()_state() returns an int error code. > > pinctrl_get_select() returns a pointer, or an error code encoded into a > pointer. > > ERR_PTR(ret) is used to convert pinctrl_select()'s int error code into > a pointer representation of the error code for pinctrl_get_select() to > return. > Oh, i see. You're right, sorry for the noise.
Regards Dong Aisheng
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