* Tony Lindgren <tony@xxxxxxxxxxx> [161114 12:54]: > * Tony Lindgren <tony@xxxxxxxxxxx> [161111 12:27]: > > * Linus Walleij <linus.walleij@xxxxxxxxxx> [161111 12:17]: > > > On Tue, Oct 25, 2016 at 11:02 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: > > > > Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx> > > > > > > I don't see why this is necessary? > > > > It's needed because the pin controller driver has not yet > > finished it's probe at this point. We end up calling functions > > in the device driver where no struct pinctrl_dev is yet known > > to the driver. Asking a device driver to do something before > > it's probe is done does not quite follow the Linux driver model :) > > > > > The hogging was placed inside pinctrl_register() so that any hogs > > > would be taken before it returns, so nothing else can take it > > > before the controller itself has the first chance. This semantic > > > needs to be preserved I think. > > > > > > > + schedule_delayed_work(&pctldev->hog_work, > > > > + msecs_to_jiffies(100)); > > > > > > If we arbitrarily delay, something else can go in and take the > > > pins used by the hogs before the pinctrl core? That is what > > > we want to avoid. > > > > > > Hm, 100ms seems arbitrarily chosen BTW. Can it be 1 ms? > > > 1 ns? > > > > Yeah well seems like it should not matter but the race we need > > to remove somehow. > > > > > I'm pretty sure that whatever it is that needs to happen before > > > the hog work runs can race with this delayed work under > > > some circumstances (such as slow external expanders > > > on i2c). It should be impossible for that to happen > > > and I don't think it is? > > > > Yes it's totally possible even with delay set to 0. > > > > Maybe we could add some trigger on the first consumer request > > and if that does not happen use the timer? > > Below is what I came up with for removing the race for hogs. We > can do it by not registering the pctldev until in the deferred > work, does that seem OK to you? Oops, that does not yet work, will have to look into it more. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
