linux-kernel - Re: [RFC 0/6] mailbox: add common framework and port drivers

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Date:	Sat, 15 Feb 2014 09:44:55 +0530
From:	Jassi Brar <jaswinder.singh@...aro.org>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Courtney Cavin <courtney.cavin@...ymobile.com>,
	"Anna, Suman" <s-anna@...com>,
	Rob Herring <rob.herring@...xeda.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Mark Langsdorf <mark.langsdorf@...xeda.com>,
	Tony Lindgren <tony@...mide.com>,
	"Omar Ramirez Luna (omar.ramirez@...itl.com)" 
	<omar.ramirez@...itl.com>, Pawel Moll <pawel.moll@....com>,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	Kumar Gala <galak@...eaurora.org>,
	Rob Landley <rob@...dley.net>, linux-doc@...r.kernel.org,
	devicetree@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
	Loic Pallardy <loic.pallardy@...com>,
	LeyFoon Tan <lftan.linux@...il.com>,
	Craig McGeachie <slapdau@...oo.com.au>
Subject: Re: [RFC 0/6] mailbox: add common framework and port drivers

On 15 February 2014 09:41, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> On Sat, Feb 15, 2014 at 09:27:48AM +0530, Jassi Brar wrote:
>> On 15 February 2014 09:10, Greg Kroah-Hartman
>> <gregkh@...uxfoundation.org> wrote:
>> > On Sat, Feb 15, 2014 at 09:02:07AM +0530, Jassi Brar wrote:
>> >> Hi,
>> >>
>> >> On 8 February 2014 06:20, Courtney Cavin <courtney.cavin@...ymobile.com> wrote:
>> >> > There is currently no common framework for mailbox drivers, so this is my
>> >> > attempt to come up with something suitable.  There seems to be a need for
>> >> > making this generic, so I have attempted to do just that.  Most of this is
>> >> > modeled pretty strongly after the pwm core, with some influences from the clock
>> >> > core.
>> >> >
>> >> > Looking at the existing use-cases, and some new ones, it would appear that the
>> >> > requirements here are rather simple. We need essentially two things for
>> >> > consumers:
>> >> >         - put_message
>> >> >         - callback for receiving messages
>> >> >
>> >> > The code currently uses atomic notifiers for callbacks.  The common omap core
>> >> > deals with fifos and work-queues in order to escape atomic contexts, but from
>> >> > what I can see, this is unneeded.  I am also of the opinion that the contexts
>> >> > can be much better managed in the drivers which are working with these
>> >> > contexts, rather than generically.
>> >> >
>> >> > Hopefully this will be suitable for the plethora of other drivers around the
>> >> > kernel which implement mailboxes, as well.  In any case, I'm rather interested
>> >> > to see what the rest of the world thinks.
>> >> >
>> >> > Keep in mind that while the pl320 & omap code should compile, I don't currently
>> >> > have a platform on which I can perform proper testing.  I also removed the
>> >> > context save/restore code from omap2 mailbox support, because I think it should
>> >> > be able to be done via driver suspend/resume, but haven't done a full
>> >> > investigation just yet.
>> >> >
>> >> > I'm also aware that breaking omap, just to fix it again probably isn't the best
>> >> > course of action, and I'm open to suggestions.
>> >> >
>> >> Did you try to look up the history of mailbox api development?  Google
>> >> search: 'mailbox common api'
>> >>
>> >> I (Linaro/Fujitsu), Suman Anna (TI), LeyFoon Tan (Intel), Craig
>> >> McGeachie(Broadcom) and Loic Pallardy(ST) already worked a generic
>> >> Mailbox framework and infact have controller drivers working over
>> >> them.
>> >>  For some confidentiality and some lazy and some confusion or whatever
>> >> reasons the final version of drivers and API wasn't submitted upstream
>> >> yet.
>> >
>> > Then, in all reality, it doesn't exist at all, and so, we will evaluate
>> > this submission instead.
>> >
>> > Just because you all can't send something for merging, doesn't mean you
>> > get to block someone else who has got their act together, that's not
>> > fair.
>> >
>> Yup probably not much fair. But then also one usually look for any
>> early development efforts. IIRC only I and Anna started. Others later
>> joined us looking at archives. Not to vindicate our gang though.
>>
>>  Now we could either punish us and have this api tread the same
>> development path where everyone had their requirements (and the
>> only-waiting-for-approval controller drivers to convert) .... OR we
>> could see if our/original/old API just works for the purposes of Sony
>> as well (which it will most probably) and then we could upstream it
>> with one more 'works-for-me-too'.
>
> What is stopping you submitting your patches right now?
>
Nothing. I'll freshen it up and submit today.

Thanks.
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