Pulls and drive strengths in the pinctrl world

[Linus Walleij]

On Thu, May 16, 2013 at 2:03 AM, Doug Anderson <dianders at google.com> wrote:

>> I prefer to put all the static pinctrl configuration in the pinctrl hog,
>> and only the dynamic stuff in the individual device nodes.
>>
>> I know LinusW won't like this suggestion much though:-)

(It's not that bad actually...)

> Ah right!  I forgot about hogs in this case.  That's also reasonable
> as a solution and is similar to what we've got in the tree for
> powerdown configuration of pins (I'll try to post this patch soon too,
> WIP at <https://gerrit.chromium.org/gerrit/#/c/51292/> and
> <https://gerrit.chromium.org/gerrit/#/c/51372/>.

I don't like these Gerrit patches really, it's better to move
this to the pinctrl core using hogs.

If you look in drivers/pinctr/core.c you can find this:

pinctrl_register()
{
(...)
        if (!IS_ERR(pctldev->p)) {
                pctldev->hog_default =
                        pinctrl_lookup_state(pctldev->p, PINCTRL_STATE_DEFAULT);
                if (IS_ERR(pctldev->hog_default)) {
                        dev_dbg(dev, "failed to lookup the default state\n");
                } else {
                        if (pinctrl_select_state(pctldev->p,
                                                pctldev->hog_default))
                                dev_err(dev,
                                        "failed to select default state\n");
                }

                pctldev->hog_sleep =
                        pinctrl_lookup_state(pctldev->p,
                                                    PINCTRL_STATE_SLEEP);
                if (IS_ERR(pctldev->hog_sleep))
                        dev_dbg(dev, "failed to lookup the sleep state\n");
        }

Just add another state, pctldev->hog_shutdown to this, and
add an operation pinctrl_force_poweroff() in the same spirit as
pinctrl_force_sleep() that we already have.

Add a new state to include/linux/pinctrl/pinctrl-state.h:
#define PINCTRL_STATE_POWEROFF "poweroff"

And define you pin table to hog these pins with the mentioned
default and poweroff states.

Result: pinctrl core keeps track of your offstate too.

Yours,
Linus Walleij