linux-kernel - Re: [PATCH v4 00/21] OMAP UART Patches

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Date:	Sun, 16 Sep 2012 21:36:22 +0300
From:	Felipe Balbi <balbi@...com>
To:	Paul Walmsley <paul@...an.com>
Cc:	Felipe Balbi <balbi@...com>,
	Shubhrajyoti Datta <shubhrajyoti@...com>,
	Greg KH <gregkh@...uxfoundation.org>, alan@...ux.intel.com,
	Tony Lindgren <tony@...mide.com>,
	Kevin Hilman <khilman@...com>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel Mailing List 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-serial@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Sourav Poddar <sourav.poddar@...com>
Subject: Re: [PATCH v4 00/21] OMAP UART Patches

Hi,

On Sun, Sep 16, 2012 at 01:22:01AM +0000, Paul Walmsley wrote:
> On Wed, 12 Sep 2012, Felipe Balbi wrote:
> 
> > On Tue, Sep 11, 2012 at 10:02:48PM +0000, Paul Walmsley wrote:
> > 
> > > The bad news is that N800 no longer boots -- or the UART dies during 
> > > serial init:
> > > 
> > > http://www.pwsan.com/omap/testlogs/test_tty_next_e36851d0/20120910020323/boot/2420n800/2420n800_log.txt
> > > 
> > > The problem doesn't seem to affect the 2430SDP.
> > > 
> > > Could you put together a patch to fix N800?
> 
> Bisected this down.  It's this one that causes the problem on N800:
> 
> commit 93220dcc3052182e7156c09655ad1316055564b9
> Author: Felipe Balbi <balbi@...com>
> Date:   Thu Sep 6 15:45:27 2012 +0300
> 
>     serial: omap: set dev->drvdata before enabling pm_runtime
>     
>     by the time we call our first pm_runtme_get_sync()
>     after enable pm_runtime, our resume method might
>     be called. To avoid problems, we must make sure
>     that our dev->drvdata is set correctly before
>     our resume method gets called.
>     
>     Tested-by: Shubhrajyoti D <shubhrajyoti@...com>
>     Acked-by: Santosh Shilimkar <santosh.shilimkar@...com>
>     Signed-off-by: Felipe Balbi <balbi@...com>
>     Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Interesting. That simply moves platform_set_drvdata() to a saner
location... The only way for this to cause problems is if we're trying
to restore a context which was never saved.

Is there a way to prevent runtime_resume() to be called during probe()
if I know the HW is already enabled ? Maybe with
pm_runtime_set_active() ?

-- 
balbi

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