From mboxrd@z Thu Jan  1 00:00:00 1970
From: haojian.zhuang@gmail.com (Haojian Zhuang)
Date: Thu, 25 Nov 2010 10:30:04 +0800
Subject: [PATCH 6/7] i2c/pxa2xx: reset the chip if the bus is not free
In-Reply-To: <1290633617-15311-7-git-send-email-bigeasy@linutronix.de>
References: <1290633617-15311-1-git-send-email-bigeasy@linutronix.de>
	<1290633617-15311-7-git-send-email-bigeasy@linutronix.de>
Message-ID: <AANLkTikvN+==eTkoh7CTQyN0mbfvPhH6Uh9NX5QW7WFx@mail.gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, Nov 25, 2010 at 5:20 AM, Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
> I haven't seen this (yet) during a normal transfer but starting
> i2cdetect seems to hang the bus. On my Sodaville board, i2cdetect runs
> fine on bus zero and runs into timeouts on bus one and two. The chip
> never recovers from this condition. The following transfers hang as
> well. The ISR_UB never disappears.
> Issuing a chip reset fixes the timeout and following transfer succeed.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
> ---
> ?drivers/i2c/busses/i2c-pxa.c | ? 35 +++++++++++++++++++----------------
> ?1 files changed, 19 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index bd4b885..1a48470 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -257,23 +257,7 @@ static void i2c_pxa_abort(struct pxa_i2c *i2c)
> ? ? ? ? ? ? ? _ICR(i2c));
> ?}
>
> -static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
> -{
> - ? ? ? int timeout = DEF_TIMEOUT;
>
> - ? ? ? while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
> - ? ? ? ? ? ? ? if ((readl(_ISR(i2c)) & ISR_SAD) != 0)
> - ? ? ? ? ? ? ? ? ? ? ? timeout += 4;
> -
> - ? ? ? ? ? ? ? msleep(2);
> - ? ? ? ? ? ? ? show_state(i2c);
> - ? ? ? }
> -
> - ? ? ? if (timeout < 0)
> - ? ? ? ? ? ? ? show_state(i2c);
> -
> - ? ? ? return timeout < 0 ? I2C_RETRY : 0;
> -}
>
> ?static int i2c_pxa_wait_master(struct pxa_i2c *i2c)
> ?{
> @@ -425,6 +409,25 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
> ? ? ? ?udelay(100);
> ?}
>
> +static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
> +{
> + ? ? ? int timeout = DEF_TIMEOUT;
> +
> + ? ? ? while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
> + ? ? ? ? ? ? ? if ((readl(_ISR(i2c)) & ISR_SAD) != 0)
> + ? ? ? ? ? ? ? ? ? ? ? timeout += 4;
> +
> + ? ? ? ? ? ? ? msleep(2);
> + ? ? ? ? ? ? ? show_state(i2c);
> + ? ? ? }
> +
> + ? ? ? if (timeout < 0) {
> + ? ? ? ? ? ? ? show_state(i2c);
> + ? ? ? ? ? ? ? i2c_pxa_reset(i2c);
> + ? ? ? }

Even you reset I2C controller, it shouldn't help you since bus isn't
free. I thinkt that you should reset I2C bus before you reseting I2C
controller.

> +
> + ? ? ? return timeout < 0 ? I2C_RETRY : 0;
> +}
>
> ?#ifdef CONFIG_I2C_PXA_SLAVE
> ?/*
> --
> 1.7.3.2
>
>
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