From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.179]) by ozlabs.org (Postfix) with ESMTP id 0D310DDE1D for ; Tue, 10 Jul 2007 16:22:06 +1000 (EST) Received: by wa-out-1112.google.com with SMTP id m28so1634573wag for ; Mon, 09 Jul 2007 23:22:05 -0700 (PDT) Message-ID: Date: Tue, 10 Jul 2007 00:22:05 -0600 From: "Grant Likely" Sender: glikely@secretlab.ca To: "Domen Puncer" Subject: Re: [PATCH] i2c-mpc: work around missing-9th-clock-pulse bug In-Reply-To: <20070710061736.GG4186@moe.telargo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed References: <20070709071955.GD4186@moe.telargo.com> <20070710061736.GG4186@moe.telargo.com> Cc: khali@linux-fr.org, i2c@lm-sensors.org, linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 7/10/07, Domen Puncer wrote: > On 09/07/07 09:53 -0600, Grant Likely wrote: > > On 7/9/07, Domen Puncer 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 Looks good to me, Acked-by: Grant Likely > > --- > 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(); > -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd. grant.likely@secretlab.ca (403) 399-0195