Re: [PATCH 1/4] i2c: designware: No need to disable already disabled controller

Wolfram Sang
2014-06-02T16:12:47Z

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On Thu, May 15, 2014 at 05:37:21PM +0300, Mika Westerberg wrote:
> If the controller is already in desired state (enabled/disabled) there is
> no point in setting its state again.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---

Does it have a side-effect when setting then enable bit again? Otherwise
it will exit the loop immediately on the first try. Not too bad IMO
given the additional code saved.

> drivers/i2c/busses/i2c-designware-core.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index b58ecf19e767..b0792675b970 100644
> --- a/drivers/i2c/busses/i2c-designware-core.c
> +++ b/drivers/i2c/busses/i2c-designware-core.c
> @@ -258,6 +258,10 @@ static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)
> {
> int timeout = 100;
>
> + /* In case the controller is already in desired state */
> + if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == enable)
> + return;
> +
> do {
> dw_writel(dev, enable, DW_IC_ENABLE);
> if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == enable)
> --
> 2.0.0.rc2
>

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