[PATCH] ARM: dts: stm32: Prefer HW RTC on DHCOM SoM

[Alexandre TORGUE]

On 6/20/21 8:54 PM, Marek Vasut wrote:
> The DHCOM SoM has two RTC, one is the STM32 RTC built into the SoC
> and another is Microcrystal RV RTC. By default, only the later has
> battery backup, the former does not. The order in which the RTCs
> are probed on boot is random, which means the kernel might pick up
> system time from the STM32 RTC which has no battery backup. This
> then leads to incorrect initial system time setup, even though the
> HW RTC has correct time configured in it.
> 
> Add DT alias entries, so that the RTCs get assigned fixed IDs and
> the HW RTC is always picked by the kernel as the default RTC, thus
> resulting in correct system time in early userspace.
> 
> Fixes: 34e0c7847dcf ("ARM: dts: stm32: Add DH Electronics DHCOM STM32MP1 SoM and PDK2 board")
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Alexandre Torgue <alexandre.torgue at foss.st.com>
> Cc: Patrice Chotard <patrice.chotard at foss.st.com>
> Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
> Cc: linux-stm32 at st-md-mailman.stormreply.com
> To: linux-arm-kernel at lists.infradead.org
> ---
>   arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
> index 2af0a6752674..8349c9099e30 100644
> --- a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
> +++ b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi
> @@ -12,6 +12,8 @@ / {
>   	aliases {
>   		ethernet0 = &ethernet0;
>   		ethernet1 = &ksz8851;
> +		rtc0 = &hwrtc;
> +		rtc1 = &rtc;
>   	};
>   
>   	memory at c0000000 {
> @@ -248,7 +250,7 @@ &i2c4 {
>   	/delete-property/dmas;
>   	/delete-property/dma-names;
>   
> -	rtc at 32 {
> +	hwrtc: rtc at 32 {
>   		compatible = "microcrystal,rv8803";
>   		reg = <0x32>;
>   	};
> 

Applied on stm32-next.

regards
alex