Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752936AbaKCP1t (ORCPT ); Mon, 3 Nov 2014 10:27:49 -0500 Received: from mga14.intel.com ([192.55.52.115]:7383 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752470AbaKCP1r (ORCPT ); Mon, 3 Nov 2014 10:27:47 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="410419383" Date: Mon, 3 Nov 2014 17:27:43 +0200 From: Mika Westerberg To: Felipe Balbi Cc: David Cohen , Linus Walleij , "linux-kernel@vger.kernel.org" , "linux-gpio@vger.kernel.org" , stable , mathias.nyman@linux.intel.com Subject: Re: [PATCH] pinctrl: baytrail: show output gpio state correctly on Intel Baytrail Message-ID: <20141103152743.GB1618@lahna.fi.intel.com> References: <20141013192632.GC29810@saruman> <20141013193618.GD29810@saruman> <20141028144249.GD8123@saruman> <20141031132005.GB1273@saruman> <20141031162339.GA7136@psi-dev26.jf.intel.com> <20141031184509.GA2224@psi-dev26.jf.intel.com> <20141103092402.GA1304@lahna.fi.intel.com> <20141103150048.GB27425@saruman> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141103150048.GB27425@saruman> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/