[PATCH V2 13/14] ARM: dts: stm32: Adjust PLL4 settings on AV96

[Patrice CHOTARD]

Hi Marek

On 3/31/20 2:48 AM, Marek Vasut wrote:
> The PLL4 is supplying SDMMC12, SDMMC3 and SPDIF with 120 MHz and
> FDCAN with 96 MHz. This isn't good for the SDMMC interfaces, which
> can not easily divide the clock down to e.g. 50 MHz for high speed
> SD and eMMC devices, so those devices end up running at 30 MHz as
> that is 120 MHz / 4. Adjust the PLL4 settings such that both PLL4P
> and PLL4R run at 100 MHz instead, which is easy to divide to 50MHz
> for optimal operation of both SD and eMMC, SPDIF clock are not that
> much slower and FDCAN is also unaffected.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Patrick Delaunay <patrick.delaunay at st.com>
> Cc: Patrice Chotard <patrice.chotard at st.com>


Reviewed-by: Patrice Chotard <patrice.chotard at st.com>

Thanks

> ---
> V2: Move this patch before the split of AV96 into SoM and carrier
> ---
>  arch/arm/dts/stm32mp157a-avenger96-u-boot.dtsi | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/dts/stm32mp157a-avenger96-u-boot.dtsi b/arch/arm/dts/stm32mp157a-avenger96-u-boot.dtsi
> index 2c7dc509a3..320132a01e 100644
> --- a/arch/arm/dts/stm32mp157a-avenger96-u-boot.dtsi
> +++ b/arch/arm/dts/stm32mp157a-avenger96-u-boot.dtsi
> @@ -130,11 +130,11 @@
>  		u-boot,dm-pre-reloc;
>  	};
>  
> -	/* VCO = 480.0 MHz => P = 120, Q = 40, R = 96 */
> +	/* VCO = 600.0 MHz => P = 100, Q = 50, R = 100 */
>  	pll4: st,pll at 3 {
>  		compatible = "st,stm32mp1-pll";
>  		reg = <3>;
> -		cfg = < 1 39 3 11 4 PQR(1,1,1) >;
> +		cfg = < 1 49 5 11 5 PQR(1,1,1) >;
>  		u-boot,dm-pre-reloc;
>  	};
>  };