[v1] arm64: dts: imx8mp: use correct clock for eqos timestamping counter

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

Posted by Johannes Zink 2 years, 6 months ago

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 <j.zink@pengutronix.de>
---
 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>;
 				nvmem-cells = <&eth_mac2>;

---
base-commit: ba345b77fae7054d0cbd033283c47033e45db6d8
change-id: 20230719-imx8mp_enet_qos_use_125mhz_clock-1c4611c979ba

Best regards,
-- 
Johannes Zink <j.zink@pengutronix.de>

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

Posted by Fabio Estevam 2 years, 6 months ago

Hi Johannes,

On Wed, Jul 19, 2023 at 10:59 AM Johannes Zink <j.zink@pengutronix.de> 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 <j.zink@pengutronix.de>
> ---
>  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>;

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

Posted by Johannes Zink 2 years, 6 months ago

Hi Fabio,

On 7/19/23 16:03, Fabio Estevam wrote:
> Hi Johannes,
> 
> On Wed, Jul 19, 2023 at 10:59 AM Johannes Zink <j.zink@pengutronix.de> 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 <j.zink@pengutronix.de>
>> ---
>>   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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