From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hanjun Guo Subject: Re: [PATCH 18/20] clocksource / acpi: Add macro CLOCKSOURCE_ACPI_DECLARE Date: Fri, 24 Jan 2014 23:53:34 +0800 Message-ID: <52E28C7E.5070509@linaro.org> References: <1389961514-13562-1-git-send-email-hanjun.guo@linaro.org> <1389961514-13562-19-git-send-email-hanjun.guo@linaro.org> <20140122114537.GA15591@e106331-lin.cambridge.arm.com> <52E1B1DE.5050507@linaro.org> <20140124120815.GH814@e106331-lin.cambridge.arm.com> <20140124151513.GD19052@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20140124151513.GD19052@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Catalin Marinas Cc: Mark Rutland , Linus Walleij , "Rafael J. Wysocki" , Will Deacon , Russell King - ARM Linux , ACPI Devel Maling List , "linux-arm-kernel@lists.infradead.org" , "grant.likely@linaro.org" , Matthew Garrett , Olof Johansson , Bjorn Helgaas , Rob Herring , Arnd Bergmann , Patch Tracking , "linux-kernel@vger.kernel.org" , linaro-kernel , "linaro-acpi@lists.linaro.org" , Charles Garcia-Tobin , Amit Daniel Kachhap List-Id: linux-acpi@vger.kernel.org On 2014=E5=B9=B401=E6=9C=8824=E6=97=A5 23:15, Catalin Marinas wrote: > On Fri, Jan 24, 2014 at 12:08:15PM +0000, Mark Rutland wrote: >> On Fri, Jan 24, 2014 at 12:20:46AM +0000, Hanjun Guo wrote: >>> On 2014=E5=B9=B401=E6=9C=8822=E6=97=A5 19:45, Mark Rutland wrote: >>>> On Wed, Jan 22, 2014 at 08:26:50AM +0000, Linus Walleij wrote: >>>>> On Fri, Jan 17, 2014 at 1:25 PM, Hanjun Guo wrote: >>>>> >>>>>> From: Amit Daniel Kachhap >>>>>> >>>>>> This macro does the same job as CLOCKSOURCE_OF_DECLARE. The devi= ce >>>>>> name from the ACPI timer table is matched with all the registere= d >>>>>> timer controllers and matching initialisation routine is invoked= =2E >>>>>> >>>>>> Signed-off-by: Amit Daniel Kachhap >>>>>> Signed-off-by: Hanjun Guo >>>>> Actually I have a fat patch renaming CLOCKSOURCE_OF_DECLARE() >>>>> to TIMER_OF_DECLARE() and I think this macro, if needed, should >>>>> be named TIMER_ACPI_DECLARE(). >>>>> >>>>> The reason is that "clocksource" is a Linux-internal name and thi= s >>>>> macro pertains to the hardware name in respective system >>>>> description type. >>>>> >>>>>> +#ifdef CONFIG_ACPI >>>>>> +#define CLOCKSOURCE_ACPI_DECLARE(name, compat, fn) = \ >>>>>> + static const struct acpi_device_id __clksrc_acpi_table_#= #name \ >>>>>> + __used __section(__clksrc_acpi_table) = \ >>>>>> + =3D { .id =3D compat, = \ >>>>>> + .driver_data =3D (kernel_ulong_t)fn } >>>>>> +#else >>>>>> +#define CLOCKSOURCE_ACPI_DECLARE(name, compat, fn) >>>>>> +#endif >>>>> This hammers down the world to compile one binary for ACPI >>>>> and one binary for device tree. Maybe that's fine, I don't know. >>>> How does it do that? >>>> >>>> As far as I could tell CONFIG_ACPI and CONFIG_OF are not mutually >>>> exclusive, and this just means that we only build the datastructur= es for >>>> matching from ACPI when CONFIG_ACPI is enabled. >>>> >>>> Have I missed something? >>>> >>>> I definitely don't want to see mutually exclusive ACPI and DT supp= ort. >>> ACPI and DT did the same job so I think they should mutually exclus= ive. >>> if we enable both DT and ACPI in one system, this will leading conf= usions. >> ACPI and DT do similar jobs, and we should be mutually exclusive at >> runtime. However, they should not be mutually exclusive at compile-t= ime. >> >> Being mutually exclusive at compile-time is just broken. It creates = more >> work for distributions (who need to ship double the number of kernel= s), >> it increases the number of configurations requiring testing, and it >> makes it easier for bugs to be introduced. It's just painful, and >> there's no reason for it. > I fully agree (IOW, I'll NAK patches that break this assumption; we w= ant > single kernel image whether it uses DT or ACPI). I will not break this in next version, because I totally agree with Mar= k=20 too :) > >> At boot time the kernel needs to decide which to use for hardware >> description, and completely ignore the other (which should not be >> present, but lets not assume that or inevitably someone will break t= hat >> assumption for a quick hack). >> >> The same kernel should boot on a system that has a DTB or a system t= hat >> has ACPI tables. On a system that's provided both it should use one = or >> the other, but not both. > Do we still need the chosen node to be passed via DT for command line= , > even if the kernel uses ACPI? It depends, but I would prefer not. I prefer UEFI+ACPI and then we don'= t=20 need the chosen node to be passed via DT. Thanks Hanjun