[Adding Jarkko, just in case he has concerns about this]
On Wed, May 20, 2015 at 10:33:13PM +0800, Jisheng Zhang wrote:
> Commit 1fc2fe204cb9 ("i2c: designware: Add runtime PM hooks") adds
> runtime pm support using the same ops for system pm and runtime pm.
> When suspend to ram, the i2c host may have been runtime suspended, thus
> i2c_dw_disable() hangs.
>
> Previously, I fixed this issue by separating ops for system pm and
> runtime pm, then in the system suspend/resume path, runtime pm apis are
> used to ensure the device is at correct state.
>
> But as Mika Westerberg pointed out: it sounds a bit silly to resume the
> device just because you want to call i2c_dw_disable() for it before
> suspending again. He then suggested an elegant solution which keeps the
> device runtime suspended during system suspend with the help of
> 'dev->power.direct_complete'. This patch adopted this solution, and in
> fact Mika provided the main code.
>
> Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
> ---
> v2 change:
> - adopt Mika's suggestion to make use of direct_complete flag
>
> drivers/i2c/busses/i2c-designware-platdrv.c | 33 +++++++++++++++++++++++++----
> 1 file changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 0a80e4a..f89650f 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -298,6 +298,22 @@ static const struct of_device_id dw_i2c_of_match[] = {
> MODULE_DEVICE_TABLE(of, dw_i2c_of_match);
> #endif
>
> +#ifdef CONFIG_PM_SLEEP
> +static int dw_i2c_prepare(struct device *dev)
> +{
> + return pm_runtime_suspended(dev);
> +}
> +
> +static void dw_i2c_complete(struct device *dev)
> +{
> + if (dev->power.direct_complete)
> + pm_request_resume(dev);
> +}
> +#else
> +#define dw_i2c_prepare NULL
> +#define dw_i2c_complete NULL
> +#endif
> +
> #ifdef CONFIG_PM
> static int dw_i2c_suspend(struct device *dev)
> {
> @@ -322,10 +338,19 @@ static int dw_i2c_resume(struct device *dev)
>
> return 0;
> }
> -#endif
>
> -static UNIVERSAL_DEV_PM_OPS(dw_i2c_dev_pm_ops, dw_i2c_suspend,
> - dw_i2c_resume, NULL);
> +static const struct dev_pm_ops dw_i2c_dev_pm_ops = {
> + .prepare = dw_i2c_prepare,
> + .complete = dw_i2c_complete,
> + SET_SYSTEM_SLEEP_PM_OPS(dw_i2c_suspend, dw_i2c_resume)
> + SET_RUNTIME_PM_OPS(dw_i2c_suspend,
> + dw_i2c_resume, NULL)
No need to wrap here. It will fit into 80 chars limit.
Otherwise looks good to me. I also tested this on Braswell and Skylake
machines where it didn't cause any problems,
Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> +};
> +
> +#define DW_I2C_DEV_PMOPS (&dw_i2c_dev_pm_ops)
> +#else
> +#define DW_I2C_DEV_PMOPS NULL
> +#endif
>
> /* work with hotplug and coldplug */
> MODULE_ALIAS("platform:i2c_designware");
> @@ -337,7 +362,7 @@ static struct platform_driver dw_i2c_driver = {
> .name = "i2c_designware",
> .of_match_table = of_match_ptr(dw_i2c_of_match),
> .acpi_match_table = ACPI_PTR(dw_i2c_acpi_match),
> - .pm = &dw_i2c_dev_pm_ops,
> + .pm = DW_I2C_DEV_PMOPS,
> },
> };
>
> --
> 2.1.4
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