From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933181AbcDYRq5 (ORCPT ); Mon, 25 Apr 2016 13:46:57 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:41017 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754558AbcDYRq4 (ORCPT ); Mon, 25 Apr 2016 13:46:56 -0400 Date: Mon, 25 Apr 2016 10:46:54 -0700 From: Darren Hart To: Giedrius =?utf-8?Q?Statkevi=C4=8Dius?= Cc: Andy Shevchenko , Corentin Chary , acpi4asus-user@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] asus-laptop: correct error handling in asus_read_brightness() Message-ID: <20160425174654.GD2115@f23x64.localdomain> References: <1460766432-5390-1-git-send-email-giedrius.statkevicius@gmail.com> <20160422074329.GA15499@tyrael> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20160422074329.GA15499@tyrael> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 22, 2016 at 10:43:30AM +0300, Giedrius Statkevičius wrote: > On Fri, Apr 22, 2016 at 02:09:22AM +0300, Andy Shevchenko wrote: > > On Sat, Apr 16, 2016 at 3:27 AM, Giedrius Statkevičius > > wrote: > > > It is possible that acpi_evaluate_integer might fail and value would not be > > > set to any value so correct this defect by returning 0 in case of an > > > error. This is also the correct thing to return because the backlight > > > subsystem will print the old value of brightness in this case. > > > > > > Signed-off-by: Giedrius Statkevičius > > > --- > > > drivers/platform/x86/asus-laptop.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c > > > index 9a69734..15f1311 100644 > > > --- a/drivers/platform/x86/asus-laptop.c > > > +++ b/drivers/platform/x86/asus-laptop.c > > > @@ -775,8 +775,10 @@ static int asus_read_brightness(struct backlight_device *bd) > > > > > > rv = acpi_evaluate_integer(asus->handle, METHOD_BRIGHTNESS_GET, > > > NULL, &value); > > > - if (ACPI_FAILURE(rv)) > > > + if (ACPI_FAILURE(rv)) { > > > pr_warn("Error reading brightness\n"); > > > + return 0; > > > + } > > > > This looks like a workaround. > > I suppose the real fix is to return here an error code and fix all callers, like > > drivers/video/backlight/backlight.c. > > > > It just fixes the behaviour according to the current code in that file. I > suppose that would be nice but I don't think it would make any difference > because the backlight core code still prints out ->props.brightness in case > ops->get_brightness fails. Just the difference would be that now actual error > messages are printed in the drivers themselves instead of generic messages from > the backlight core. Anyway, I think the current behaviour is more useful because > the drivers know better about what has failed. > As a matter of practice, based on feedback from the previous pdx86 maintainers, I prefer to accept patches which fix an immediate issue and leave the rework or broader work as a follow-on, or a TODO item. We should look for a good place to document these TODOs. Queued for 4.7. Thanks, -- Darren Hart Intel Open Source Technology Center