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From: Maxime Coquelin <maxime.coquelin@st.com>
To: Daniel Thompson <daniel.thompson@linaro.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-serial@vger.kernel.org
Cc: patches@linaro.org, linaro-kernel@lists.linaro.org,
	linux-kernel@vger.kernel.org,
	Srinivas Kandagatla <srinivas.kandagatla@gmail.com>,
	Patrice Chotard <patrice.chotard@st.com>,
	Jiri Slaby <jslaby@suse.cz>,
	linux-arm-kernel@lists.infradead.org, kernel@stlinux.com
Subject: Re: [PATCH] serial: st-asc: Fix data corruption during long console bursts
Date: Tue, 13 May 2014 18:28:22 +0200	[thread overview]
Message-ID: <53724826.9000907@st.com> (raw)
In-Reply-To: <1399997337-27950-1-git-send-email-daniel.thompson@linaro.org>

Hi Daniel,

On 05/13/2014 06:08 PM, Daniel Thompson wrote:
> On my test platform (B2020/STiH416) the serial port issues bad characters
> during the initial message avalanche as the console comes up. The problem
> also occurs when dense(ish) I/O is done using the polled I/O interface.
>
> The problem is fixed for me by using the FIFO half-empty bit rather than
> FIFO full bit. Note that using the half-empty bit causes the FIFO to be
> managed in a similar way to interrupt based I/O (i.e. where the hardware
> gets best test coverage).
>
> Running the FIFO half full will have no impact (good or bad) on console
> performance. The UART will still remain fully saturated and the busy-wait
> until the FIFO is empty in asc_console_write() will complete at the same
> time.
>
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
>   drivers/tty/serial/st-asc.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>

Acked-by: Maxime Coquelin <maxime.coquelin@st.com>

Thanks!
Maxime

WARNING: multiple messages have this Message-ID (diff)
From: maxime.coquelin@st.com (Maxime Coquelin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] serial: st-asc: Fix data corruption during long console bursts
Date: Tue, 13 May 2014 18:28:22 +0200	[thread overview]
Message-ID: <53724826.9000907@st.com> (raw)
In-Reply-To: <1399997337-27950-1-git-send-email-daniel.thompson@linaro.org>

Hi Daniel,

On 05/13/2014 06:08 PM, Daniel Thompson wrote:
> On my test platform (B2020/STiH416) the serial port issues bad characters
> during the initial message avalanche as the console comes up. The problem
> also occurs when dense(ish) I/O is done using the polled I/O interface.
>
> The problem is fixed for me by using the FIFO half-empty bit rather than
> FIFO full bit. Note that using the half-empty bit causes the FIFO to be
> managed in a similar way to interrupt based I/O (i.e. where the hardware
> gets best test coverage).
>
> Running the FIFO half full will have no impact (good or bad) on console
> performance. The UART will still remain fully saturated and the busy-wait
> until the FIFO is empty in asc_console_write() will complete at the same
> time.
>
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
>   drivers/tty/serial/st-asc.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>

Acked-by: Maxime Coquelin <maxime.coquelin@st.com>

Thanks!
Maxime

WARNING: multiple messages have this Message-ID (diff)
From: Maxime Coquelin <maxime.coquelin@st.com>
To: Daniel Thompson <daniel.thompson@linaro.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	<linux-serial@vger.kernel.org>
Cc: <patches@linaro.org>, <linaro-kernel@lists.linaro.org>,
	<linux-kernel@vger.kernel.org>,
	Srinivas Kandagatla <srinivas.kandagatla@gmail.com>,
	Patrice Chotard <patrice.chotard@st.com>,
	Jiri Slaby <jslaby@suse.cz>,
	<linux-arm-kernel@lists.infradead.org>, <kernel@stlinux.com>
Subject: Re: [PATCH] serial: st-asc: Fix data corruption during long console bursts
Date: Tue, 13 May 2014 18:28:22 +0200	[thread overview]
Message-ID: <53724826.9000907@st.com> (raw)
In-Reply-To: <1399997337-27950-1-git-send-email-daniel.thompson@linaro.org>

Hi Daniel,

On 05/13/2014 06:08 PM, Daniel Thompson wrote:
> On my test platform (B2020/STiH416) the serial port issues bad characters
> during the initial message avalanche as the console comes up. The problem
> also occurs when dense(ish) I/O is done using the polled I/O interface.
>
> The problem is fixed for me by using the FIFO half-empty bit rather than
> FIFO full bit. Note that using the half-empty bit causes the FIFO to be
> managed in a similar way to interrupt based I/O (i.e. where the hardware
> gets best test coverage).
>
> Running the FIFO half full will have no impact (good or bad) on console
> performance. The UART will still remain fully saturated and the busy-wait
> until the FIFO is empty in asc_console_write() will complete at the same
> time.
>
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> ---
>   drivers/tty/serial/st-asc.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>

Acked-by: Maxime Coquelin <maxime.coquelin@st.com>

Thanks!
Maxime

  reply	other threads:[~2014-05-13 16:29 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-13 16:08 [PATCH] serial: st-asc: Fix data corruption during long console bursts Daniel Thompson
2014-05-13 16:08 ` Daniel Thompson
2014-05-13 16:28 ` Maxime Coquelin [this message]
2014-05-13 16:28   ` Maxime Coquelin
2014-05-13 16:28   ` Maxime Coquelin

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