Hi,
I don't think it is worth backporting this patch to 4.4. Cutting VDD
core will only happen after mainline v4.12 or v4.9 for the vendor kernel.
On 25/09/2017 at 01:13:43 +0000, Levin, Alexander (Sasha Levin) wrote:
> From: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
>
> [ Upstream commit e3ccc921b7d8fd1fcd10a00720e09823d8078666 ]
>
> When going to suspend, the I2C registers may be lost because the power to
> VDDcore is cut. Restore them when resuming.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> Acked-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
> Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-at91.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
> index 10835d1f559b..dee0fc421054 100644
> --- a/drivers/i2c/busses/i2c-at91.c
> +++ b/drivers/i2c/busses/i2c-at91.c
> @@ -1131,6 +1131,7 @@ static int at91_twi_suspend_noirq(struct device *dev)
>
> static int at91_twi_resume_noirq(struct device *dev)
> {
> + struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
> int ret;
>
> if (!pm_runtime_status_suspended(dev)) {
> @@ -1142,6 +1143,8 @@ static int at91_twi_resume_noirq(struct device *dev)
> pm_runtime_mark_last_busy(dev);
> pm_request_autosuspend(dev);
>
> + at91_init_twi_bus(twi_dev);
> +
> return 0;
> }
>
> --
> 2.11.0
--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com