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Date:   Tue, 26 Mar 2019 10:34:58 +0900
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     stable@vger.kernel.org, Jiri Slaby <jslaby@suse.com>,
        Orson Zhai <orsonzhai@gmail.com>,
        Baolin Wang <baolin.wang@linaro.org>,
        Chunyan Zhang <zhang.lyra@gmail.com>,
        Lanqing Liu <lanqing.liu@spreadtrum.com>,
        Chunyan Zhang <chunyan.zhang@spreadtrum.com>,
        Lanqing Liu <lanqing.liu@unisoc.com>,
        linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [BACKPORT 4.4.y 23/25] serial: sprd: clear timeout interrupt
 only rather than all interrupts
Message-ID: <20190326013458.GC21198@kroah.com>
References: <20190322154425.3852517-1-arnd@arndb.de>
 <20190322154425.3852517-24-arnd@arndb.de>
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On Fri, Mar 22, 2019 at 04:44:14PM +0100, Arnd Bergmann wrote:
> From: Lanqing Liu <lanqing.liu@spreadtrum.com>
> 
> On Spreadtrum's serial device, nearly all of interrupts would be cleared
> by hardware except timeout interrupt.  This patch removed the operation
> of clearing all interrupt in irq handler, instead added an if statement
> to check if the timeout interrupt is supposed to be cleared.
> 
> Wrongly clearing timeout interrupt would lead to uart data stay in rx
> fifo, that means the driver cannot read them out anymore.
> 
> Signed-off-by: Lanqing Liu <lanqing.liu@spreadtrum.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> (cherry picked from commit 4350782570b919f254c1e083261a21c19fcaee90)
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/tty/serial/sprd_serial.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Also added to 4.9.y