linux-kernel - Re: [PATCH 3/3] omap: add hwspinlock device

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Message-ID: <20101022170330.GC9445@angua.secretlab.ca>
Date:	Fri, 22 Oct 2010 11:03:30 -0600
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Ohad Ben-Cohen <ohad@...ery.com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Balaji T K <balajitk@...com>,
	"Kamat, Nishant" <nskamat@...com>, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	akpm@...ux-foundation.org, Greg KH <greg@...ah.com>,
	Benoit Cousson <b-cousson@...com>,
	Hari Kanigeri <h-kanigeri2@...com>, Suman Anna <s-anna@...com>,
	Simon Que <sque@...com>
Subject: Re: [PATCH 3/3] omap: add hwspinlock device

On Fri, Oct 22, 2010 at 09:56:13AM -0700, Tony Lindgren wrote:
> * Ohad Ben-Cohen <ohad@...ery.com> [101020 12:12]:
> > On Wed, Oct 20, 2010 at 8:37 PM, Kevin Hilman
> > <khilman@...prootsystems.com> wrote:
> > >> Let's take the i2c-omap for example.
> > >>
> > >> It sounds like it must have a predefined hwspinlock, but what if:
> > >>
> > >> 1. It will use omap_hwspinlock_request() to dynamically allocate a hwspinlock
> > >> 2. Obviously, the hwspinlock id number must be communicated to the M3
> > >> BIOS, so the i2c-omap will publish that id using a small shared memory
> > >> entry that will be allocated for this sole purpose
> > >> 3. we will make sure that 1+2 completes before the remote processor is
> > >> taken out of reset
> 
> Guys, let's try to come up with a generic interface for this instead of
> polluting the device drivers with more omap specific interfaces.
> 
> We really want to keep the drivers generic and platform independent.
> 
> Sure we still have some omap specific stuff in the drivers, like
> cpu_is_omapxxxx, and omap specific dma calls, but those will be going
> away.
> 
> Unless somebody has better ideas, I suggest we pass a lock function
> in the platform_data to the drivers that need it, and do the omap
> specific nasty stuff in the platform code.

For those of you going to plumbers, I'll put this on the embedded
microconference agenda when we're talking about common infrastructure.

g.

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