[PATCH] drivers: create a pin control subsystem v8
linus.walleij at linaro.org
Fri Sep 30 15:05:20 UTC 2011
On Fri, Sep 30, 2011 at 4:07 AM, Grant Likely <grant.likely at secretlab.ca> wrote:
> Comments below, some a bit nitpicky, but overall I think it looks
> good. I haven't dug into it nearly deeply enough though. :-(
Hopefully we can patch the remaining bugs as we go along :-)
>> + * Looks up a pin control device matching a certain device name or
>> + * pure device pointer.
> May as well actually do kerneldoc formatting here on the comment
>> +struct pinctrl_dev *get_pctldev_from_dev(struct device *dev,
>> + const char *devname)
> Nit: I'm not too fond of a single function doing both name and pointer
> lookup at the same time. Presumably the caller would have one or the
> other and know what it needs to do. I'd prefer to see one by-name
> function and one by-reference. I'm not going to make a big deal about
> it though.
The caller currently does not know what it has or
what to do.
This is basically an interator function that is called on
a member tuple of device and device name to check
which one you have and return a matching controller
device for the key you do have.
>> + /* Register device with sysfs */
>> + pctldev->dev.parent = dev;
>> + pctldev->dev.bus = &pinctrl_bus;
> I don't think there is an actual need for a pinctrl bus type. There
> aren't any drivers that are going to be bound to these things which is
> the primary functionality that a bus type provides. Am I missing
That is not the reason it's there actually, what we have
discussed on the mailing list is getting sysfs entries for the same
reason gpiolib registers a class: handle pin control from userspace,
we can already see that coming and I already have a use case
for it. (Modem SIM connector control from userspace daemon.)
So first it was registering a class, then Greg said classes are
deprecated and we should use a bus instead. So it is
registering a bus to get sysfs so we can get userspace
>> + put_device(&pctldev->dev);
>> + kfree(pctldev);
> Once a device is initialized, it cannot be kfree()'ed directly. The
> .release method needs to do that.
OK. And I already had a proper .release() method doing
exactly that, so deleting this.
>> + * pin_free() - release a single muxed in pin so something else can be muxed in
>> + * instead
> Nit: the summary line in kerneldoc should fit on one line.
Went over the code and fixed a few other sites too.
>> +int __init
>> +pinmux_register_mappings(struct pinmux_map const *maps, unsigned num_maps)
> Nit: keep line breaks in the parameter lists. More grep friendly.
OK fixed it.
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