linux-kernel - Re: [PATCH] pch_uart: Fix dma channel unallocated issue

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Message-ID: <20120410144110.GE14703@kroah.com>
Date:	Tue, 10 Apr 2012 07:41:10 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Tomoya MORINAGA <tomoya.rohm@...il.com>
Cc:	Alan Cox <alan@...ux.intel.com>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, qi.wang@...el.com,
	yong.y.wang@...el.com, joel.clark@...el.com, kok.howg.ewe@...el.com
Subject: Re: [PATCH] pch_uart: Fix dma channel unallocated issue

On Tue, Apr 10, 2012 at 10:26:25AM +0900, Tomoya MORINAGA wrote:
> On Tue, Apr 10, 2012 at 2:44 AM, Greg Kroah-Hartman
> <gregkh@...uxfoundation.org> wrote:
> >> This driver anticipates pch_uart_verify_port() is not called
> >> during installation.
> >> However, actually pch_uart_verify_port() is called during
> >> installation.
> >> As a result, memory access violation occurs like below.
> >>
> >> 0. initial value: use_dma=0
> >> 1. starup()
> >>     - dma channel is not allocated because use_dma=0
> >> 2. pch_uart_verify_port()
> >>     - Set use_dma=1
> >> 3. UART processing acts DMA mode because use_dma=1
> >>      - memory access violation occurs!
> >>
> >> This patch fixes the issue.
> >>
> >> Solution:
> >> Whenever pch_uart_verify_port() is called and then
> >> dma channel is not allocated, the channel should be allocated.
> >>
> >> Signed-off-by: Tomoya MORINAGA <tomoya.rohm@...il.com>
> >> ---
> >>  drivers/tty/serial/pch_uart.c |    4 +++-
> >>  1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > This patch does not apply to 3.4-rc2, so I can not apply it, sorry.
> >
> > Care to redo it?
> 
> This patch depends on the following patch you've already accepted.
> 
> >From 44db113212d86a5870c2bfe8fb767fa842d68805 Mon Sep 17 00:00:00 2001
> From: Tomoya MORINAGA <tomoya.rohm@...il.com>
> Date: Mon, 26 Mar 2012 14:43:00 +0900
> Subject: pch_uart: Delete unused structure member
> 
> Signed-off-by: Tomoya MORINAGA <tomoya.rohm@...il.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> ---
>  drivers/tty/serial/pch_uart.c |    2 --
>  1 file changed, 2 deletions(-)
> 
> 
> So now,  this patch can be applied.
> In fact, I've confirmed this patch can be applied to 3.4-rc2 with the
> following order.
> 1st: pch_uart: Delete unused structure member

That patch is not applicable for the 3.4-release.

> 2nd: pch_uart: Fix dma channel unallocated issue

But I thought this one would be, which is why I did not try to apply
anything else before it.

> I should have written the dependency.

Yes, you always should.

> Could you try to apply this patch again ?

Don't you want this patch in the 3.4-final release?  If so, I need it
without the dependancy.

thanks,

greg k-h
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