linux-kernel - Re: [PATCH v2 2/5] ARM: zynq: dt: Convert to preprocessor includes

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Date:	Thu, 10 Apr 2014 12:44:20 +0200
From:	Michal Simek <monstr@...str.eu>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
CC:	Steffen Trumtrar <s.trumtrar@...gutronix.de>,
	Mike Looijmans <mike.looijmans@...ic.nl>,
	Mark Rutland <mark.rutland@....com>,
	devicetree@...r.kernel.org, Russell King <linux@....linux.org.uk>,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Michal Simek <michal.simek@...inx.com>,
	linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	Kumar Gala <galak@...eaurora.org>,
	Soren Brinkmann <soren.brinkmann@...inx.com>
Subject: Re: [PATCH v2 2/5] ARM: zynq: dt: Convert to preprocessor includes

On 04/08/2014 07:27 PM, Jason Gunthorpe wrote:
> On Tue, Apr 08, 2014 at 09:03:27AM +0200, Michal Simek wrote:
> 
>>> If in doubt follow common mainline practice. Although using includes
>>> for DT is not necessarily common practice, readability of DTs is
>>> really important IMHO.
>>
>> Let me give you one example. When you add xilinx intc controller
>> to zynq HW design which uses gic with headers you are using
>> then you will find out that sensitivity for both controllers
>> are just different.
>> This is just one case I am aware of. I expect there will be one more.
> 
> I'm not sure I see the problem here, just because some bindings can't
> use the standard shared constants doesn't mean the GIC bindings and
> users should avoid them. The binding documentation is supposed to make
> it clear what is correct.
> 
> It is just as easy to get confused with numbers, does 4 mean
> XILINX_INTC_IRQ_RISING or IRQ_TYPE_LEVEL_HIGH ?

That's why you have there biding documentation to exactly know what it is.

>> Using dtc preprocessor and macros improve DTS readability but at the same
>> time force other users to copy all necessary files from the kernel
>> to that projects which is just hassle.
> 
> You can run the DTS through cpp before you export it out of the kernel
> environment, then you get a flat file with no includes.

What's the result?
1. DTSI and DTS together which completely break hierarchy
2. DTS without comments

It means, yes, you get a file when you go through cpp but different
then you have now.

> The shared kernel conventions are more important than constraints from
> outside projects.

zynq-7000.dtsi is fixed and you can't just change it based on your project.
For things which are in your board file like zynq-zc702 then you can use
whatever you like.

Maybe I just need some time to get used to it but currently...

Thanks,
Michal

-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform



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