[PATCH] [I2C] OMAP: Don't write IE state in unidle if 0

[PATCH] [I2C] OMAP: Don't write IE state in unidle if 0

[Cory Maccarrone]

Commit ef871432... (i2c-omap: OMAP3: PM: (re)init for every transfer
to support off-mode) introduced a change which make the dev->iestate
contents be written to the OMAP_I2C_IE_REG every time omap_i2c_unidle
is called.  Previously, the state was only written if it wasn't equal
to zero.

In omap_i2c_probe, omap_i2c_unidle() is called prior to omap_i2c_init(),
in which case dev->iestate has not yet been initialized and will be set
to zero.  Having this value written to the registers causes deadlock
while booting.

As such, this change restores the original functionality.

Signed-off-by: Cory Maccarrone <darkstar6262-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/i2c-omap.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 3440d88..c0bb9eb 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -248,7 +248,13 @@ static void omap_i2c_unidle(struct omap_i2c_dev *dev)
 		omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
 	}
 	dev->idle = 0;
-	omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
+
+	/*
+	 * Don't write to this register if the IE state is 0 as it can
+	 * cause deadlock.
+	 */
+	if (dev->iestate)
+		omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
 }
 
 static void omap_i2c_idle(struct omap_i2c_dev *dev)
-- 
1.6.3.3

Re: [PATCH] [I2C] OMAP: Don't write IE state in unidle if 0

[Tony Lindgren]

* Cory Maccarrone <darkstar6262@gmail.com> [091222 17:05]:
> Commit ef871432... (i2c-omap: OMAP3: PM: (re)init for every transfer
> to support off-mode) introduced a change which make the dev->iestate
> contents be written to the OMAP_I2C_IE_REG every time omap_i2c_unidle
> is called.  Previously, the state was only written if it wasn't equal
> to zero.
> 
> In omap_i2c_probe, omap_i2c_unidle() is called prior to omap_i2c_init(),
> in which case dev->iestate has not yet been initialized and will be set
> to zero.  Having this value written to the registers causes deadlock
> while booting.
> 
> As such, this change restores the original functionality.

Looks like initializing dev->iestate to something before calling
omap_i2c_unidle in omap_i2c_probe is not an option in this case.
We'd want to initialize it to zero, which causes the deadlock..

Acked-by: Tony Lindgren <tony@atomide.com>


> 
> Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
> ---
>  drivers/i2c/busses/i2c-omap.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 3440d88..c0bb9eb 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -248,7 +248,13 @@ static void omap_i2c_unidle(struct omap_i2c_dev *dev)
>  		omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
>  	}
>  	dev->idle = 0;
> -	omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
> +
> +	/*
> +	 * Don't write to this register if the IE state is 0 as it can
> +	 * cause deadlock.
> +	 */
> +	if (dev->iestate)
> +		omap_i2c_write_reg(dev, OMAP_I2C_IE_REG, dev->iestate);
>  }
>  
>  static void omap_i2c_idle(struct omap_i2c_dev *dev)
> -- 
> 1.6.3.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html