From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bh-25.webhostbox.net ([208.91.199.152]:44670 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752258AbcDHNSJ (ORCPT ); Fri, 8 Apr 2016 09:18:09 -0400 Subject: Re: [PATCH 04/10] iio: stx104: Change STX104 dependency to ISA_BUS To: William Breathitt Gray References: <783be62acf68b35f3fe4785a2cedfe017624688b.1460040201.git.vilhelm.gray@gmail.com> <20160408004503.GB10211@roeck-us.net> <20160408123158.GB18202@sophia> Cc: gregkh@linuxfoundation.org, tglx@linutronix.de, jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, wim@iguana.be, linus.walleij@linaro.org, gnurou@gmail.com, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-gpio@vger.kernel.org From: Guenter Roeck Message-ID: <5707AF91.5010704@roeck-us.net> Date: Fri, 8 Apr 2016 06:18:09 -0700 MIME-Version: 1.0 In-Reply-To: <20160408123158.GB18202@sophia> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 04/08/2016 05:31 AM, William Breathitt Gray wrote: > On Thu, Apr 07, 2016 at 05:45:03PM -0700, Guenter Roeck wrote: >> This means for this and other similar drivers that the driver is no longer >> supported on architectures which support ISA but not the newly introduced >> ISA_BUS. Affected architectures are alpha, arm, m32r, m68k, mips, powerpc, >> and parisc. >> >> A typical example is SCSI_AHA1542, which is no longer supported on those >> architectures. It builds, but isa_register_driver() will be a dummy and fail. >> Actually, this is true for _all_ drivers calling isa_register_driver(). >> >> I hope this is understood and doesn't cause any problems. >> >> Thanks, >> Guenter > > That's a good catch. I overlooked this when I submitted the ISA_BUS > patch; I had improperly assumed the ISA option to have a dependency on > X86_32 based on arch/x86/Kconfig. The intention of the ISA_BUS is to > allow the proper definition of the isa_register_driver and > isa_unregister_driver functions without the dependency on X86_32 (e.g. > on X86_64 systems). How can this be resolved without ending support for > ISA on these other architectures? Would it be appropriate to add the > ISA_BUS dependency to every "config ISA" block for the other > architectures? > From the context, arm and mips use "select ISA". For those, adding and auto-selecting ISA_BUS would make sense. For the remaining architectures you could simply add "config ISA_BUS". I would suggest to update default configurations, though. There is also "um", for which you effectively disabled ISA support as far as I can see. You might want to look into that as well. > My avoidance of making ISA a selection of ISA_BUS is the possibility of > an invalid configuration: a user may initially enable ISA_BUS, then > later disable ISA, resulting in ISA_BUS remaining enabled without ISA > selected. > Does that even make sense ? Not sure I understand why you don't just select ISA_BUS if ISA is selected. That would also be backward compatible and avoid the problem I was concerned about. > As a side note, should the dummy isa_register_driver return 0? Would it > be more appropriate for it to return an error code to indicate lack of > support for ISA, rather than silently fail? > One should think so. Thanks, Guenter