linux-kernel - Re: [PATCH V2 01/10] Documentation: dt-bindings: mailbox: tegra: Add binding for HSP mailbox

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Date:	Mon, 11 Jul 2016 10:08:08 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Rob Herring <robh@...nel.org>
Cc:	Sivaram Nair <sivaramn@...dia.com>, Joseph Lo <josephl@...dia.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>,
	linux-tegra@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Mark Rutland <mark.rutland@....com>,
	Peter De Schrijver <pdeschrijver@...dia.com>,
	Matthew Longnecker <MLongnecker@...dia.com>,
	devicetree@...r.kernel.org, Jassi Brar <jassisinghbrar@...il.com>,
	linux-kernel@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>
Subject: Re: [PATCH V2 01/10] Documentation: dt-bindings: mailbox: tegra: Add
 binding for HSP mailbox

On 07/11/2016 08:14 AM, Rob Herring wrote:
> On Thu, Jul 07, 2016 at 12:35:02PM -0600, Stephen Warren wrote:
>> On 07/07/2016 12:13 PM, Sivaram Nair wrote:
>>> On Tue, Jul 05, 2016 at 05:04:22PM +0800, Joseph Lo wrote:
>>>> Add DT binding for the Hardware Synchronization Primitives (HSP). The
>>>> HSP is designed for the processors to share resources and communicate
>>>> together. It provides a set of hardware synchronization primitives for
>>>> interprocessor communication. So the interprocessor communication (IPC)
>>>> protocols can use hardware synchronization primitive, when operating
>>>> between two processors not in an SMP relationship.
>>
>>>> diff --git a/include/dt-bindings/mailbox/tegra186-hsp.h b/include/dt-bindings/mailbox/tegra186-hsp.h
>>
>>>> +#define HSP_MBOX_TYPE_DB 0x0
>>>> +#define HSP_MBOX_TYPE_SM 0x1
>>>> +#define HSP_MBOX_TYPE_SS 0x2
>>>> +#define HSP_MBOX_TYPE_AS 0x3
>>>> +
>>>> +#define HSP_DB_MASTER_CCPLEX 17
>>>> +#define HSP_DB_MASTER_BPMP 19
>>>> +
>>>> +#define HSP_MBOX_ID(type, ID) \
>>>> +		(HSP_MBOX_TYPE_##type << 16 | ID)
>>>
>>> It will be nicer if you avoid the macro glue magic '##' for 'type'. I
>>> would also suggest to use braces around 'type' and 'ID'.
>>
>> This technique been used without issue in quite a few other places without
>> issue, and has the benefit of simplifying the text wherever the macro is
>> used. What issue do you foresee?
>
> I'm not a fan of using the macros to begin with and less so anything
> more complex than a single constant value. I'd rather see 2 cells here
> with the first being the id and the 2nd being the type.
>
> An issue with token pasting is grepping for DB, SM, etc. in kernel tree
> is probably noisy. Not such a big deal here, but a major PIA when you
> have more complex sets of includes.

Is that a NAK or simply a suggestion? Having a single cell makes DT 
parsing a bit simpler, since pretty much every SW stack provides a 
default "one-cell" of_xlate implementation, whereas >1 cell means custom 
code for of_xlate.