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

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>
---
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(-)

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;
>  	};
>  };

Hi Marek,

> From: Marek Vasut <marex at denx.de>
> Sent: mardi 31 mars 2020 02:49
> 
> 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>
> ---
> V2: Move this patch before the split of AV96 into SoM and carrier
> ---

Reviewed-by: Patrick Delaunay <patrick.delaunay at st.com>

Thanks

Patrick