From: Domen Puncer <domen.puncer@telargo•com>
To: Grant Likely <grant.likely@secretlab•ca>
Cc: khali@linux-fr•org, i2c@lm-sensors•org, linuxppc-embedded@ozlabs•org
Subject: Re: [PATCH] i2c-mpc: work around missing-9th-clock-pulse bug
Date: Tue, 10 Jul 2007 08:17:36 +0200 [thread overview]
Message-ID: <20070710061736.GG4186@moe.telargo.com> (raw)
In-Reply-To: <fa686aa40707090853j6079b0c7rbcff7c449baa15e0@mail.gmail.com>
On 09/07/07 09:53 -0600, Grant Likely wrote:
> On 7/9/07, Domen Puncer <domen.puncer@telargo•com> wrote:
> >Work around a problem reported on:
> >http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html
> >Without this patch I2C on mpc5200 becomes unusable after a while.
> >Tested on mpc5200 based boards by Matthias and me.
> >
> >Index: work-powerpc.git/drivers/i2c/busses/i2c-mpc.c
> >===================================================================
> >--- work-powerpc.git.orig/drivers/i2c/busses/i2c-mpc.c
> >+++ work-powerpc.git/drivers/i2c/busses/i2c-mpc.c
> >@@ -153,6 +167,9 @@ static void mpc_i2c_start(struct mpc_i2c
> > static void mpc_i2c_stop(struct mpc_i2c *i2c)
> > {
> > writeccr(i2c, CCR_MEN);
> >+ mb();
> >+ writeccr(i2c, 0);
> >+ mb();
> > }
>
> Are the mb() calls necessary? The writeccr path includes eieio; is
> that not sufficient?
Right, v2:
Work around a problem reported on:
http://ozlabs.org/pipermail/linuxppc-embedded/2005-July/019038.html
Without this patch I2C on mpc5200 becomes unusable after a while.
Tested on mpc5200 boards by Matthias and me.
Signed-off-by: Domen Puncer <domen.puncer@telargo•com>
---
drivers/i2c/busses/i2c-mpc.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
Index: work-powerpc.git/drivers/i2c/busses/i2c-mpc.c
===================================================================
--- work-powerpc.git.orig/drivers/i2c/busses/i2c-mpc.c
+++ work-powerpc.git/drivers/i2c/busses/i2c-mpc.c
@@ -74,6 +74,20 @@ static irqreturn_t mpc_i2c_isr(int irq,
return IRQ_HANDLED;
}
+static void mpc_i2c_fixup(struct mpc_i2c *i2c)
+{
+ writeccr(i2c, 0);
+ udelay(30);
+ writeccr(i2c, CCR_MEN);
+ udelay(30);
+ writeccr(i2c, CCR_MSTA | CCR_MTX);
+ udelay(30);
+ writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN);
+ udelay(30);
+ writeccr(i2c, CCR_MEN);
+ udelay(30);
+}
+
static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing)
{
unsigned long orig_jiffies = jiffies;
@@ -153,6 +167,7 @@ static void mpc_i2c_start(struct mpc_i2c
static void mpc_i2c_stop(struct mpc_i2c *i2c)
{
writeccr(i2c, CCR_MEN);
+ writeccr(i2c, 0);
}
static int mpc_write(struct mpc_i2c *i2c, int target,
@@ -245,6 +260,8 @@ static int mpc_xfer(struct i2c_adapter *
}
if (time_after(jiffies, orig_jiffies + HZ)) {
pr_debug("I2C: timeout\n");
+ if (readb(i2c->base + MPC_I2C_SR) == (CSR_MCF | CSR_MBB | CSR_RXAK))
+ mpc_i2c_fixup(i2c);
return -EIO;
}
schedule();
next prev parent reply other threads:[~2007-07-10 6:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-09 7:19 [PATCH] i2c-mpc: work around missing-9th-clock-pulse bug Domen Puncer
2007-07-09 15:53 ` Grant Likely
2007-07-10 6:17 ` Domen Puncer [this message]
2007-07-10 6:22 ` Grant Likely
2007-07-10 12:40 ` Jean Delvare
2007-07-11 5:49 ` Domen Puncer
2007-07-11 6:03 ` Grant Likely
2007-07-11 6:33 ` Domen Puncer
2007-07-11 11:40 ` Jean Delvare
2007-07-21 0:03 ` [i2c] " Guennadi Liakhovetski
2007-07-24 5:14 ` [PATCH] i2c-mpc: don't disable I2C module on stop condition Domen Puncer
2007-08-08 17:19 ` Jean Delvare
2007-08-08 18:33 ` Guennadi Liakhovetski
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