netdev - Re: [PATCH 2/4] dt-bindings: net: can: Make interrupt attributes optional for MCAN

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Message-ID: <20230420-zoom-demystify-c31d6bf25295-mkl@pengutronix.de>
Date:   Thu, 20 Apr 2023 12:01:07 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Judith Mendez <jm@...com>
Cc:     Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Schuyler Patton <spatton@...com>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-can@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 2/4] dt-bindings: net: can: Make interrupt attributes
 optional for MCAN

On 19.04.2023 17:33:21, Judith Mendez wrote:
> For MCAN, remove interrupt and interrupt names from the required
> section.
> 
> On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
> routed to A53 Linux, instead they will use software interrupt
> by hrtimer. Make interrupt attributes optional in MCAN node
> by removing from required section.
> 
> Signed-off-by: Judith Mendez <jm@...com>

This series basically adds polling support to the driver, which is
needed due to HW limitations.

The proposed logic in the driver is to use polling if
platform_get_irq_byname() fails (due to whatever reason) use polling
with a hard-coded interval.

In the kernel I've found the following properties that describe the
polling interval:

bindings/input/input.yaml:

|   poll-interval:
|     description: Poll interval time in milliseconds.
|     $ref: /schemas/types.yaml#/definitions/uint32


bindings/thermal/thermal-zones.yaml:

|       polling-delay:
|         $ref: /schemas/types.yaml#/definitions/uint32
|         description:
|           The maximum number of milliseconds to wait between polls when
|           checking this thermal zone. Setting this to 0 disables the polling
|           timers setup by the thermal framework and assumes that the thermal
|           sensors in this zone support interrupts.

bindings/regulator/dlg,da9121.yaml

|   dlg,irq-polling-delay-passive-ms:
|     minimum: 1000
|     maximum: 10000
|     description: |
|       Specify the polling period, measured in milliseconds, between interrupt status
|       update checks. Range 1000-10000 ms.

From my point of view the poll-interval from the input subsystem looks
good. Any objections to use it to specify the polling interval for
IRQ-less devices, too?

> ---
>  Documentation/devicetree/bindings/net/can/bosch,m_can.yaml | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
> index 67879aab623b..43f1aa9addc0 100644
> --- a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
> +++ b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
> @@ -122,8 +122,6 @@ required:
>    - compatible
>    - reg
>    - reg-names
> -  - interrupts
> -  - interrupt-names
>    - clocks
>    - clock-names
>    - bosch,mram-cfg
> -- 
> 2.17.1
> 
> 

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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