Re: [PATCH] arm64: dts: imx93: update default value for snps,clk-csr

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Am Mittwoch, 10. Juli 2024, 22:08:33 CEST schrieb Shenwei Wang:
> For the i.MX93 SoC, the clock rate for the IP of STMMAC EQOS is 315 MHz.

Are you talking about enet_qos (IMX93_CLK_ENET_QOS_GATE)?
Downstream 6.1 kernel shows:
 sys_pll_pfd2                         1        1        0   625000000          0     0  50000         Y
    wakeup_axi_root                   4        4        0   312500000          0     0  50000         Y
       enet_qos                       5        5        0   312500000          0     0  50000         Y

Also RM gives a maximum of 312.5 MHz.

> According to the following mapping table from the i.MX93 reference manual,
> this clock rate corresponds to a CSR value of 6.
> 
>  0100: CSR clock = 150-250 MHz; MDC clock = CSR clock/102
>  0101: CSR clock = 250-300 MHz; MDC clock = CSR clock/124
>  0110: CSR clock = 300-500 MHz; MDC clock = CSR clock/204
>  0111: CSR clock = 500-800 MHz; MDC clock = CSR clock/324

As the old value is 0 you should at least add that entry as well.

But AFAICS enet_qos is passed as clock 'mem' to this device.
So instead of hard-coding this into DT, this divider should be calculated from actual
enet_qos clock.

Best regards,
Alexander

> Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com>
> ---
>  arch/arm64/boot/dts/freescale/imx93.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx93.dtsi b/arch/arm64/boot/dts/freescale/imx93.dtsi
> index 4a3f42355cb8..a0993022c102 100644
> --- a/arch/arm64/boot/dts/freescale/imx93.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx93.dtsi
> @@ -1105,7 +1105,7 @@ eqos: ethernet@428a0000 {
>  							 <&clk IMX93_CLK_SYS_PLL_PFD0_DIV2>;
>  				assigned-clock-rates = <100000000>, <250000000>;
>  				intf_mode = <&wakeupmix_gpr 0x28>;
> -				snps,clk-csr = <0>;
> +				snps,clk-csr = <6>;
>  				nvmem-cells = <&eth_mac2>;
>  				nvmem-cell-names = "mac-address";
>  				status = "disabled";
> 


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