Hi,

On Mon, Aug 15, 2011 at 11:49:32AM -0700, Doug Anderson wrote:
> This change doesn't fix any known problems but turns
> on the overflow detection feature of the i2c controller
> in the hopes of flushing out any current (or future)
> bugs in the i2c driver.
> 
> Inspired by a change on nvidia's git server:
>   
> http://nv-tegra.nvidia.com/gitweb/?p=linux-2.6.git;a=commit;h=266d1b7397284505e55d06254b497cb32be07b69
> 
> Signed-off-by: Doug Anderson <[email protected]>
> ---
>  drivers/i2c/busses/i2c-tegra.c |   11 ++++++++---
>  1 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 2440b74..4dbba23 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -367,7 +367,8 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
>  static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>  {
>       u32 status;
> -     const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
> +     const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST |
> +             I2C_INT_TX_FIFO_OVERFLOW;
>       struct tegra_i2c_dev *i2c_dev = dev_id;
>  
>       status = i2c_readl(i2c_dev, I2C_INT_STATUS);
> @@ -389,6 +390,9 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>       }
>  
>       if (unlikely(status & status_err)) {
> +             /* Don't pass this back--it can only happen due to a bug. */
> +             BUG_ON(status & I2C_INT_TX_FIFO_OVERFLOW);

so due to a FIFO overflow you lock up the whole system ? Can't you e.g.
reset the controller and reconfigure it rather than locking up the
system ?

-- 
balbi

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