linux-kernel - Re: [PATCH -mm v4 6/9] atmel_serial: Split the interrupt handler

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Message-ID: <20080130164631.7de4f6bd@dhcp-252-066.norway.atmel.com>
Date:	Wed, 30 Jan 2008 16:46:31 +0100
From:	Haavard Skinnemoen <hskinnemoen@...el.com>
To:	michael <trimarchi@...dalf.sssup.it>
Cc:	Remy Bohmer <linux@...mer.net>, fabio@...dalf.sssup.it,
	Andrew Victor <linux@...im.org.za>,
	Chip Coldwell <coldwell@...hat.com>,
	Marc Pignat <marc.pignat@...s.ch>,
	David Brownell <david-b@...bell.net>,
	linux-kernel@...r.kernel.org, Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH -mm v4 6/9] atmel_serial: Split the interrupt handler

On Wed, 30 Jan 2008 16:26:27 +0100
michael <trimarchi@...dalf.sssup.it> wrote:

> > I have no idea. Could you post some more specifics about what you
> > modified, for example a diff?
> >
> >     
> 
> ...
> /* The interrupt handler does not take the lock */
> spin_lock_irqsave(&port->lock, flags);
> atmel_tx_chars(port);
> spin_unlock_irqrestore(&port->lock, flags);

Sorry, this isn't going to work.

Please post a diff with the changes you did to the driver, and whatever
output you got when it crashed.

It's really difficult to help you when I don't know (a) what code
you're actually running, or (b) anything about the crash.

> The atmel_tx_chars using the serial device registers like the interrupt 
> routine
> and so I think that it is possible to have interference during send 
> operation.

No, it's only called from the tasklet, and the interrupt handler doesn't
touch the TX data register. There shouldn't be any need to disable
interrupts around the call to atmel_tx_chars(). In fact, this may very
well be the cause of the overruns you're seeing.

Haavard
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