linux-kernel - Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)

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Message-ID: <20110621124742.GK7920@linux-sh.org>
Date:	Tue, 21 Jun 2011 21:47:43 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Magnus Damm <magnus.damm@...il.com>,
	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Paul Walmsley <paul@...an.com>, Kevin Hilman <khilman@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	LKML <linux-kernel@...r.kernel.org>, linux-sh@...r.kernel.org
Subject: Re: [Update][PATCH 8/8] ARM / shmobile: Support for I/O power domains for SH7372 (v6)

On Tue, Jun 21, 2011 at 01:57:08PM +0200, Rafael J. Wysocki wrote:
> On Tuesday, June 21, 2011, Rafael J. Wysocki wrote:
> > On Monday, June 20, 2011, Paul Mundt wrote:
> > > Given that these functions can return errors, it's probably more prudent
> > > to implement some timeout logic on top of the busy loop. Hardware does
> > > get stuck, after all.
> > 
> > Yes, it does, but we don't really know what timeout value to use in there.
> > 
> > In fact, failures of pd_power_down() don't really matter (at worst the power
> > domain won't be powered off really) and pd_power_up() should only return error
> > code if the error is known to be unrecoverable.
> > 
> > So, what about this: repeat certain number of times (I verified that it took
> > several iterations of the loop until the new value settled on my hardware)
> > and then return from pd_power_down() or go to sleep for a short time and repeat
> > in pd_power_up()?
> 
> Having discussed that with Magnus I changed pd_power_down() to use a timeout.
> Specifically, it will bail out if the state doesn't change after approximately
> 1 ms.
> 
Looks good to me, thanks for fixing it up.

Acked-by: Paul Mundt <lethal@...ux-sh.org>
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