From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752920AbaKXO63 (ORCPT ); Mon, 24 Nov 2014 09:58:29 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:61711 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751530AbaKXO61 (ORCPT ); Mon, 24 Nov 2014 09:58:27 -0500 From: "Rafael J. Wysocki" To: Aaron Lu Cc: Lee Jones , Jacob Pan , Yegnesh Iyer , linux-acpi@vger.kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Lv Zheng Subject: Re: [PATCH v3 updated 3/3] ACPI / PMIC: AXP288: support virtual GPIO in ACPI table Date: Mon, 24 Nov 2014 16:19:39 +0100 Message-ID: <2204417.orosXAozvY@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.16.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <5472FB31.8000408@intel.com> References: <1416553911-22990-1-git-send-email-aaron.lu@intel.com> <1648486.coeVgHKNdn@vostro.rjw.lan> <5472FB31.8000408@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday, November 24, 2014 05:32:33 PM Aaron Lu wrote: > On 11/24/2014 09:06 AM, Rafael J. Wysocki wrote: > > On Friday, November 21, 2014 03:11:51 PM Aaron Lu wrote: > >> + if (!result) { > >> + status = acpi_install_address_space_handler( > >> + ACPI_HANDLE(parent), ACPI_ADR_SPACE_GPIO, > >> + intel_xpower_pmic_gpio_handler, NULL, NULL); > > > > So here we have a problem, because we can't unregister the opregion handler > > registered above if this fails. Not nice. > > I'm not correct in the cover letter, the actual problem with operation > region remove is with module unload, it happens like this: > > The acpi_remove_address_space_handler doesn't wait for the current > running handler to return, so if we call > acpi_remove_address_space_handler in a module's exit function, the > handler's memory will be freed and the running handler will access to > a no longer valid memory place. > > So as long as we can make sure the handler will not go away from the > memory, we are safe. This only means that address space handlers cannot be removed from kernel modules. Lv was trying to add a wrapper for that some time ago, maybe it's a good idea to revive that? > With this said, the updated patch is here: > > From: Aaron Lu > Date: Mon, 20 Oct 2014 17:06:20 +0800 > Subject: [PATCH 3/3] ACPI / PMIC: AXP288: support virtual GPIO in ACPI table > > The same virtual GPIO strategy is also used for the AXP288 PMIC in that > various control methods that are used to do power rail handling and > sensor reading/setting will touch GPIO fields defined under the PMIC > device. The GPIO fileds are only defined by the ACPI code while the > actual hardware doesn't really have a GPIO controller, but to make those > control method execution succeed, we have to install a GPIO handler for > the PMIC device handle. Since we do not need the virtual GPIO strategy, > we can simply do nothing in that handler. > > Signed-off-by: Aaron Lu > --- > drivers/acpi/pmic/intel_pmic_xpower.c | 30 ++++++++++++++++++++++++++---- > 1 file changed, 26 insertions(+), 4 deletions(-) > > diff --git a/drivers/acpi/pmic/intel_pmic_xpower.c b/drivers/acpi/pmic/intel_pmic_xpower.c > index 795ca073db08..9ec57ebd81c9 100644 > --- a/drivers/acpi/pmic/intel_pmic_xpower.c > +++ b/drivers/acpi/pmic/intel_pmic_xpower.c > @@ -220,13 +220,35 @@ static struct intel_pmic_opregion_data intel_xpower_pmic_opregion_data = { > .thermal_table_count = ARRAY_SIZE(thermal_table), > }; > > +static acpi_status intel_xpower_pmic_gpio_handler(u32 function, > + acpi_physical_address address, u32 bit_width, u64 *value, > + void *handler_context, void *region_context) > +{ > + return AE_OK; > +} > > static int intel_xpower_pmic_opregion_probe(struct platform_device *pdev) > { > - struct axp20x_dev *axp20x = dev_get_drvdata(pdev->dev.parent); > - return intel_pmic_install_opregion_handler(&pdev->dev, > - ACPI_HANDLE(pdev->dev.parent), axp20x->regmap, > - &intel_xpower_pmic_opregion_data); > + struct device *parent = pdev->dev.parent; > + struct axp20x_dev *axp20x = dev_get_drvdata(parent); > + acpi_status status; > + int result; > + > + status = acpi_install_address_space_handler(ACPI_HANDLE(parent), > + ACPI_ADR_SPACE_GPIO, intel_xpower_pmic_gpio_handler, > + NULL, NULL); > + if (ACPI_FAILURE(status)) > + return -ENODEV; > + > + result = intel_pmic_install_opregion_handler(&pdev->dev, > + ACPI_HANDLE(parent), axp20x->regmap, > + &intel_xpower_pmic_opregion_data); > + if (result) > + acpi_remove_address_space_handler(ACPI_HANDLE(parent), > + ACPI_ADR_SPACE_GPIO, > + intel_xpower_pmic_gpio_handler); > + > + return result; > } > > static struct platform_driver intel_xpower_pmic_opregion_driver = { > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.