Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751436AbaKDGWN (ORCPT ); Tue, 4 Nov 2014 01:22:13 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:59934 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750911AbaKDGWJ (ORCPT ); Tue, 4 Nov 2014 01:22:09 -0500 Date: Mon, 3 Nov 2014 22:21:37 -0800 From: Darren Hart To: Azael Avalos , rjw@rjwysocki.net, linux-acpi@vger.kernel.org Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, Nuno Lopes Subject: Re: [PATCH] toshiba_acpi: Fix regression caused by backlight extra check code Message-ID: <20141104062137.GC56751@vmdeb7> References: <1415073514-12555-1-git-send-email-coproscefalo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1415073514-12555-1-git-send-email-coproscefalo@gmail.com> 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 08:58:34PM -0700, Azael Avalos wrote: > Bug 86521 uncovered that some TOS6208 devices also return > non zero values on a write call to the backlight method, > thus getting caught and bailed out by the extra check code. > > This patch makes sure that the extra check is being done > on a TOS1900 device and then make the check for the broken > backlight code. > > Signed-off-by: Azael Avalos > --- > drivers/platform/x86/toshiba_acpi.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c > index ef3a190..e3fed12 100644 > --- a/drivers/platform/x86/toshiba_acpi.c > +++ b/drivers/platform/x86/toshiba_acpi.c > @@ -944,9 +944,13 @@ static int set_lcd_brightness(struct toshiba_acpi_dev *dev, int value) > /* Extra check for "incomplete" backlight method, where the AML code > * doesn't check for HCI_SET or HCI_GET and returns TOS_SUCCESS, > * the actual brightness, and in some cases the max brightness. > + * Use the SPFC method as an indicator that we're on a TOS1900 device, > + * otherwise some TOS6208 devices might get bailed out, see bug 86521 This needs a clearer description here in this comment, rather than redirecting the reader to a bug report (which may or may not exist when needed). > */ > - if (out[2] > 0 || out[3] == 0xE000) > - return -ENODEV; > + if (acpi_has_method(dev->acpi_dev->handle, "SPFC")) { Hrm, this checking for the existence of a specific method seems suspect to me. We would know if we are on a TOS1900 as we matches the acpi id already. Is the SPFC significant here, or is it just a "we only see SPFC on TOS1900 so it's a convenient test"? If the latter, it seems rather fragile and prone to other breakage to me. Rafael, any recommendations here? > + if (out[2] > 0 || out[3] == 0xE000) > + return -ENODEV; > + } > > return out[0] == TOS_SUCCESS ? 0 : -EIO; > } > -- > 2.1.1 > > -- Darren Hart Intel Open Source Technology Center -- 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/