[PATCH] arm64: dts: imx8mp: Clarify csis clock frequency

[Laurent Pinchart]

On Thu, Aug 15, 2024 at 02:12:09PM +0200, Alexander Stein wrote:
> Am Mittwoch, 14. August 2024, 01:40:10 CEST schrieb Laurent Pinchart:
> > The DT nodes for the MIPI CSI-2 receivers (MIPI_CSI) configure the
> > CAM1_PIX and CAM2_PIX clocks to 266 MHz through the assigned-clock-rates
> > property, and report that frequency in the clock-frequency property. The
> > i.MX8MP reference manual and datasheet list 266 MHz as a nominal
> > frequency when using both CSI-2 receivers, so all looks normal.
> > 
> > In reality, the clock is actually set to 250 MHz, as the selected
> > parent, IMX8MP_SYS_PLL2_1000M, has a 1/4 output that is selected as the
> > closest frequency to 266 MHz. This doesn't break operation of the
> > device, but is clearly misleading.
> > 
> > Clarify the clock configuration by selecting the IMX8MP_SYS_PLL2_250M
> > parent, dropping the redundant assigned-clock-rates, and setting
> > clock-frequency to 250 MHz. This doesn't cause any functional change.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8mp.dtsi | 10 ++++------
> >  1 file changed, 4 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > index 603dfe80216f..d9b5c40f6460 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > @@ -1687,7 +1687,7 @@ mipi_csi_0: csi at 32e40000 {
> >  				compatible = "fsl,imx8mp-mipi-csi2", "fsl,imx8mm-mipi-csi2";
> >  				reg = <0x32e40000 0x10000>;
> >  				interrupts = <GIC_SPI 17 IRQ_TYPE_LEVEL_HIGH>;
> > -				clock-frequency = <266000000>;
> > +				clock-frequency = <250000000>;
> 
> This doesn't seem to be necessary, no? I can't be read from
> IMX8MP_CLK_MEDIA_CAM1_PIX_ROOT. But oh well, that's what we have right now.

I don't like the clock frequency property much, but as it's there, I
decided to update it. Removing the property, if desired, belongs to a
separate patch.

> Despite that:
> Reviewed-by: Alexander Stein <alexander.stein at ew.tq-group.com>
> Tested-by: Alexander Stein <alexander.stein at ew.tq-group.com>

Shawn, could you please pick this up for v6.12 ?

> >  				clocks = <&clk IMX8MP_CLK_MEDIA_APB_ROOT>,
> >  					 <&clk IMX8MP_CLK_MEDIA_CAM1_PIX_ROOT>,
> >  					 <&clk IMX8MP_CLK_MEDIA_MIPI_PHY1_REF_ROOT>,
> > @@ -1695,9 +1695,8 @@ mipi_csi_0: csi at 32e40000 {
> >  				clock-names = "pclk", "wrap", "phy", "axi";
> >  				assigned-clocks = <&clk IMX8MP_CLK_MEDIA_CAM1_PIX>,
> >  						  <&clk IMX8MP_CLK_MEDIA_MIPI_PHY1_REF>;
> > -				assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_1000M>,
> > +				assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_250M>,
> >  							 <&clk IMX8MP_CLK_24M>;
> > -				assigned-clock-rates = <266000000>;
> >  				power-domains = <&media_blk_ctrl IMX8MP_MEDIABLK_PD_MIPI_CSI2_1>;
> >  				status = "disabled";
> >  
> > @@ -1723,7 +1722,7 @@ mipi_csi_1: csi at 32e50000 {
> >  				compatible = "fsl,imx8mp-mipi-csi2", "fsl,imx8mm-mipi-csi2";
> >  				reg = <0x32e50000 0x10000>;
> >  				interrupts = <GIC_SPI 80 IRQ_TYPE_LEVEL_HIGH>;
> > -				clock-frequency = <266000000>;
> > +				clock-frequency = <250000000>;
> >  				clocks = <&clk IMX8MP_CLK_MEDIA_APB_ROOT>,
> >  					 <&clk IMX8MP_CLK_MEDIA_CAM2_PIX_ROOT>,
> >  					 <&clk IMX8MP_CLK_MEDIA_MIPI_PHY1_REF_ROOT>,
> > @@ -1731,9 +1730,8 @@ mipi_csi_1: csi at 32e50000 {
> >  				clock-names = "pclk", "wrap", "phy", "axi";
> >  				assigned-clocks = <&clk IMX8MP_CLK_MEDIA_CAM2_PIX>,
> >  						  <&clk IMX8MP_CLK_MEDIA_MIPI_PHY1_REF>;
> > -				assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_1000M>,
> > +				assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_250M>,
> >  							 <&clk IMX8MP_CLK_24M>;
> > -				assigned-clock-rates = <266000000>;
> >  				power-domains = <&media_blk_ctrl IMX8MP_MEDIABLK_PD_MIPI_CSI2_2>;
> >  				status = "disabled";
> >  
> > 
> > base-commit: 7c626ce4bae1ac14f60076d00eafe71af30450ba

-- 
Regards,

Laurent Pinchart