linux-kernel - Re: [PATCH] Serial: BUGFIX: uart_resume

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Date:	Thu, 14 Oct 2010 11:45:11 -0700
From:	Greg KH <greg@...ah.com>
To:	Stanislav Brabec <sbrabec@...e.cz>
Cc:	MyungJoo Ham <myungjoo.ham@...sung.com>, Greg KH <gregkh@...e.de>,
	linux-kernel@...r.kernel.org, kyungmin.park@...sung.com,
	Alan Cox <alan@...ux.intel.com>, Arnd Bergmann <arnd@...db.de>,
	Andr Goddard Rosa <andre.goddard@...il.com>,
	Jason Wang <jason77.wang@...il.com>,
	linux-serial@...r.kernel.org
Subject: Re: [PATCH] Serial: BUGFIX: uart_resume_port has an omitted
 condition.

On Wed, Oct 13, 2010 at 01:26:45PM +0200, Stanislav Brabec wrote:
> On Wed, 13 Oct 2010 15:38:13 +0900, MyungJoo Ham wrote:
> > On Wed, Oct 13, 2010 at 3:26 PM, Greg KH <gregkh@...e.de> wrote:
> > > On Wed, Oct 13, 2010 at 02:58:06PM +0900, MyungJoo Ham wrote:
> 
> > > Is this a regression?  If so, from what working kernel?  Or has this
> > > always been this way?
> > 
> > I don't think this is a regression to the previous version. Logically,
> > it's matching the console_stop()-console_start() pair.
> 
> This disparity appeared deliberately in 4547be78. If you need
> no_console_suspend and the hardware lets the device in an undefined
> state after resume (i. e. PXA270), you need to call subset of the
> resume, even if the suspend counterpart was not called. Yes, I can
> imagine that it may be a source of problems.
> 
> Did you try the latest patches from Jason Wang from linux-serial list?
> 
> > Such hang in serial and its mitigation is observed in 2.6.36 at
> > arch/arm/mach-s5pv310 machines. In these machines, it hanged with
> > console_suspend_enabled == 0 every time.
> 
> It seems that support for no_console_suspend for all devices is becoming
> more complicated. I guess that a new driver calls (maybe "save_state"
> and "resume_state") or support for no_console_suspend directly in
> drivers may be useful.

Ok, so I'm guessing that this patch is not to be applied then, correct?

thanks,

greg k-h
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