Re: [PATCH 3/3] arm64: dts: imx8mm: Slow default video_pll1 clock rate

[Frieder Schrempf]

On 28.11.23 05:54, Adam Ford wrote:
> Since commit 8208181fe536 ("clk: imx: composite-8m:
> Add imx8m_divider_determine_rate") the lcdif controller has
> had the ability to set the lcdif_pixel rate which propagates
> up the tree and sets the video_pll1 rate automatically.
> 
> By setting this value low, it will force the recalculation of
> video_pll1 to the lowest rate needed by lcdif instead of
> dividing a larger clock down to the desired clock speed. This
> has the  advantage of being able to lower the video_pll1 rate
> from 594MHz to 148.5MHz when operating at 1080p. It can go even
> lower when operating at lower resolutions and refresh rates.
> 
> Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mm.dtsi b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> index a3dae114c20e..669fdd2c54e4 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
> @@ -1131,7 +1131,7 @@ lcdif: lcdif@32e00000 {
>  				assigned-clock-parents = <&clk IMX8MM_VIDEO_PLL1_OUT>,
>  							 <&clk IMX8MM_SYS_PLL2_1000M>,
>  							 <&clk IMX8MM_SYS_PLL1_800M>;
> -				assigned-clock-rates = <594000000>, <500000000>, <200000000>;
> +				assigned-clock-rates = <24000000>, <500000000>, <200000000>;
>  				interrupts = <GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>;
>  				power-domains = <&disp_blk_ctrl IMX8MM_DISPBLK_PD_LCDIF>;
>  				status = "disabled";

Thanks for the cleanup!

Reviewed-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
Tested-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> # Kontron BL
i.MX8MM