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

Laurent Pinchart
2024-08-13T23:40:36Z

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@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@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>;
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@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@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@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