linux-kernel - Re: [PATCH v6 11/11] arm64: dts: ti: k3-am64: Reserve timers used by MCU FW

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Message-ID: <dab7c2ae-2ce9-4fdc-933c-35a4fd92a8e5@ti.com>
Date: Mon, 7 Apr 2025 09:38:44 -0500
From: Judith Mendez <jm@...com>
To: Andrew Davis <afd@...com>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra
	<vigneshr@...com>
CC: Tero Kristo <kristo@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof
 Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Hari Nagalla <hnagalla@...com>,
        Beleswar
 Padhi <b-padhi@...com>,
        Markus Schneider-Pargmann <msp@...libre.com>
Subject: Re: [PATCH v6 11/11] arm64: dts: ti: k3-am64: Reserve timers used by
 MCU FW

Hi Andrew,

On 4/7/25 7:35 AM, Andrew Davis wrote:
> On 4/4/25 7:15 PM, Judith Mendez wrote:
>> From: Hari Nagalla <hnagalla@...com>
>>
>> AM64x device has 4 R5F cores in the main domain. TI MCU firmware uses
>> main domain timers as tick timers in these firmwares. Hence keep them
>> as reserved in the Linux device tree.
>>
>> Signed-off-by: Hari Nagalla <hnagalla@...com>
>> Signed-off-by: Judith Mendez <jm@...com>
>> ---
>>   arch/arm64/boot/dts/ti/k3-am642-evm.dts | 17 +++++++++++++++++
>>   arch/arm64/boot/dts/ti/k3-am642-sk.dts  | 17 +++++++++++++++++
>>   2 files changed, 34 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/ti/k3-am642-evm.dts 
>> b/arch/arm64/boot/dts/ti/k3-am642-evm.dts
>> index f8ec40523254b..68bd6b806f8f0 100644
>> --- a/arch/arm64/boot/dts/ti/k3-am642-evm.dts
>> +++ b/arch/arm64/boot/dts/ti/k3-am642-evm.dts
>> @@ -796,6 +796,23 @@ &mcu_m4fss {
>>       status = "okay";
>>   };
>> +/* main_timers 8-11 are used by TI MCU FW */
> 
> Can you make this comment per-core and explain which core
> each timer is reserved for? Makes it easier on me in Zephyr
> to point out why we use the timers that we do, something
> like:
> 
> /* main_timer8 is reserved for mcu_r5fss0_core0 */

Sure, I can do that. Will wait for [0] conversation to close and then
respin the series with this change

[0] 
https://lore.kernel.org/linux-devicetree/f42607f5-e39d-48a1-89c0-11d4982a2426@ti.com/

~ Judith

> 
> Andrew
> 
>> +&main_timer8 {
>> +    status = "reserved";
>> +};
>> +
>> +&main_timer9 {
>> +    status = "reserved";
>> +};
>> +
>> +&main_timer10 {
>> +    status = "reserved";
>> +};
>> +
>> +&main_timer11 {
>> +    status = "reserved";
>> +};
>> +
>>   &serdes_ln_ctrl {
>>       idle-states = <AM64_SERDES0_LANE0_PCIE0>;
>>   };
>> diff --git a/arch/arm64/boot/dts/ti/k3-am642-sk.dts 
>> b/arch/arm64/boot/dts/ti/k3-am642-sk.dts
>> index 33e421ec18abb..07fbdf2400d23 100644
>> --- a/arch/arm64/boot/dts/ti/k3-am642-sk.dts
>> +++ b/arch/arm64/boot/dts/ti/k3-am642-sk.dts
>> @@ -710,6 +710,23 @@ &mcu_m4fss {
>>       status = "okay";
>>   };
>> +/* main_timers 8-11 are used by TI MCU FW */
>> +&main_timer8 {
>> +    status = "reserved";
>> +};
>> +
>> +&main_timer9 {
>> +    status = "reserved";
>> +};
>> +
>> +&main_timer10 {
>> +    status = "reserved";
>> +};
>> +
>> +&main_timer11 {
>> +    status = "reserved";
>> +};
>> +
>>   &ecap0 {
>>       status = "okay";
>>       /* PWM is available on Pin 1 of header J3 */