From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Felipe Balbi <balbi@ti.com>
Cc: David Cohen <david.a.cohen@linux.intel.com>,
Linus Walleij <linus.walleij@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
stable <stable@vger.kernel.org>,
mathias.nyman@linux.intel.com
Subject: Re: [PATCH] pinctrl: baytrail: show output gpio state correctly on Intel Baytrail
Date: Mon, 3 Nov 2014 17:27:43 +0200 [thread overview]
Message-ID: <20141103152743.GB1618@lahna.fi.intel.com> (raw)
In-Reply-To: <20141103150048.GB27425@saruman>
On Mon, Nov 03, 2014 at 09:00:48AM -0600, Felipe Balbi wrote:
> On Mon, Nov 03, 2014 at 11:24:02AM +0200, Mika Westerberg wrote:
> > On Fri, Oct 31, 2014 at 11:45:09AM -0700, David Cohen wrote:
> > > > I think adding the module exit + allowing this driver to be a module
> > > > would be a good approach. Then we don't need to force generic x86 kernel
> > > > binaries to always have this driver. Unless Mathias or Mika knows a
> > > > constraint to force this driver to be builtin only.
> > >
> > > It helps if I CC them when asking for feedback :)
> > >
> > > Mathias, Mika, do you know any constraint that forces pinctrl-baytrail
> > > to be bool?
> >
> > The only constraint that has been keeping this driver as bool is that
> > some machines like, Asus T100, uses ACPI GPIO operation regions for
> > toggling GPIOs to get things like sensor hub powered on. The GPIO
> > operation region code does not yet handle -EPROBE_DEFER so only way to
> > ensure that the operation region is there is to have the driver compiled
> > in to the kernel.
>
> But that's not enough excuse to have every single x86 in the market
> shipping with this driver. Think about a distro kernel, most likely this
> gets enabled and it's wrong in 80% of the cases.
True, but see below.
> It would be nicer to add EPROBE_DEFER support, convert this into
> tristate and have default = M if BAYTRAIL, or something.
If it were simple as that we would have done that already. Please check
drivers/gpio/gpiolib-acpi.c:acpi_gpio_adr_space_handler() and tell me
how we can do that.
The problem is that it is *firmware* code that decides to use the GPIO
at some random point in time and we have no way to tell it to retry
later when the GPIO is available.
next prev parent reply other threads:[~2014-11-03 15:27 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 16:55 [PATCH] pinctrl: baytrail: show output gpio state correctly on Intel Baytrail David Cohen
2014-10-13 18:23 ` David Cohen
2014-10-13 19:14 ` Felipe Balbi
2014-10-13 19:24 ` David Cohen
2014-10-13 19:26 ` Felipe Balbi
2014-10-13 19:36 ` Felipe Balbi
2014-10-13 20:19 ` David Cohen
2014-10-28 10:15 ` Linus Walleij
2014-10-28 14:42 ` Felipe Balbi
2014-10-31 8:12 ` Linus Walleij
2014-10-31 13:20 ` Felipe Balbi
2014-10-31 16:23 ` David Cohen
2014-10-31 18:45 ` David Cohen
2014-11-03 9:24 ` Mika Westerberg
2014-11-03 15:00 ` Felipe Balbi
2014-11-03 15:27 ` Mika Westerberg [this message]
2014-11-03 15:35 ` Felipe Balbi
2014-11-03 15:42 ` Mika Westerberg
2014-11-03 15:50 ` Felipe Balbi
2014-11-03 18:42 ` Mika Westerberg
2014-11-03 20:40 ` Felipe Balbi
2014-11-04 7:51 ` Mika Westerberg
2014-11-04 14:44 ` Felipe Balbi
2014-11-03 22:19 ` David Cohen
2014-11-04 7:59 ` Mika Westerberg
2014-11-04 18:05 ` David Cohen
2014-11-04 18:57 ` Mika Westerberg
2014-11-04 19:11 ` David Cohen
2014-11-04 19:34 ` Mika Westerberg
2014-11-04 21:51 ` David Cohen
2014-11-05 8:40 ` Mika Westerberg
2014-11-14 9:40 ` Linus Walleij
2014-11-14 9:39 ` Linus Walleij
2014-11-14 9:53 ` Mika Westerberg
2014-11-14 23:19 ` Rafael J. Wysocki
2014-11-14 9:30 ` Linus Walleij
2014-11-03 15:33 ` Linus Walleij
2014-10-13 20:16 ` David Cohen
2014-10-14 17:54 ` [PATCH v2] " David Cohen
2014-10-14 18:19 ` Felipe Balbi
2014-10-28 10:17 ` Linus Walleij
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