2023-07-19 14:13:32

by Fabio Estevam

Subject: Re: [PATCH] arm64: dts: imx8mp: use correct clock for eqos timestamping counter

Hi Johannes,

On Wed, Jul 19, 2023 at 10:59 AM Johannes Zink <[email protected]> wrote:
>
> The i.MX8MP Reference Manual rev 1 06/2021, section 11.7.2.5 "Timestamp
> Support" indicates the PTP timestamp clock expects a typical frequency
> of 125MHz.
>
> As this also improves the precision of the measured timestamps: assign
> appropriate 125MHz Clock parent. As no one except the timestamping
> counter uses this clock, there are no side-effects of this change in
> other peripherals.
>
> Signed-off-by: Johannes Zink <[email protected]>
> ---
> arch/arm64/boot/dts/freescale/imx8mp.dtsi | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> index 6f2f50e1639c..7f80dff914c2 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> @@ -1334,7 +1334,7 @@ eqos: ethernet@30bf0000 {
> <&clk IMX8MP_CLK_ENET_QOS_TIMER>,
> <&clk IMX8MP_CLK_ENET_QOS>;
> assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_266M>,
> - <&clk IMX8MP_SYS_PLL2_100M>,
> + <&clk IMX8MP_SYS_PLL2_125M>,
> <&clk IMX8MP_SYS_PLL2_125M>;
> assigned-clock-rates = <0>, <100000000>, <125000000>;

Shouldn't this also be changed to:

assigned-clock-rates = <0>, <125000000>, <125000000>;

2023-07-19 14:30:18

by Johannes Zink

Subject: Re: [PATCH] arm64: dts: imx8mp: use correct clock for eqos timestamping counter

Hi Fabio,

On 7/19/23 16:03, Fabio Estevam wrote:
> Hi Johannes,
>
> On Wed, Jul 19, 2023 at 10:59 AM Johannes Zink <[email protected]> wrote:
>>
>> The i.MX8MP Reference Manual rev 1 06/2021, section 11.7.2.5 "Timestamp
>> Support" indicates the PTP timestamp clock expects a typical frequency
>> of 125MHz.
>>
>> As this also improves the precision of the measured timestamps: assign
>> appropriate 125MHz Clock parent. As no one except the timestamping
>> counter uses this clock, there are no side-effects of this change in
>> other peripherals.
>>
>> Signed-off-by: Johannes Zink <[email protected]>
>> ---
>> arch/arm64/boot/dts/freescale/imx8mp.dtsi | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
>> index 6f2f50e1639c..7f80dff914c2 100644
>> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
>> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
>> @@ -1334,7 +1334,7 @@ eqos: ethernet@30bf0000 {
>> <&clk IMX8MP_CLK_ENET_QOS_TIMER>,
>> <&clk IMX8MP_CLK_ENET_QOS>;
>> assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_266M>,
>> - <&clk IMX8MP_SYS_PLL2_100M>,
>> + <&clk IMX8MP_SYS_PLL2_125M>,
>> <&clk IMX8MP_SYS_PLL2_125M>;
>> assigned-clock-rates = <0>, <100000000>, <125000000>;
>
> Shouldn't this also be changed to:
>
> assigned-clock-rates = <0>, <125000000>, <125000000>;
>

good catch, thanks! Gonna fix it in v2.

Best regards
Johannes

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