Re: [PATCH 1/2] rtc: s3c: Disable all enable (RTC, tick) bits in the probe

[Krzysztof Kozlowski <krzk@kernel.org>]

On Wed, Dec 02, 2020 at 12:13:17PM +0100, Marek Szyprowski wrote:
> Bootloader might use RTC hardware and leave it in the enabled state. Ensure
> that the potentially enabled periodic tick interrupts are disabled before
> enabling the driver, because they might cause lockup if tick interrupt
> happens after disabling RTC gate clock.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
>  drivers/rtc/rtc-s3c.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-s3c.c b/drivers/rtc/rtc-s3c.c
> index 24a41909f049..16a326e95d46 100644
> --- a/drivers/rtc/rtc-s3c.c
> +++ b/drivers/rtc/rtc-s3c.c
> @@ -503,6 +503,10 @@ static int s3c_rtc_probe(struct platform_device *pdev)
>  			goto err_src_clk;
>  	}
>  
> +	/* disable RTC enable bits potentially set by the bootloader */
> +	if (info->data->disable)
> +		info->data->disable(info);
> +

It took me some time to figure out why this makes sense: disable
followed immediately by enable. :) You could add in commit msg that
enable() callback does not enable the tick interrupt.

Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>

Best regards,
Krzysztof