linux-kernel - Re: [PATCH v6 2/2] can: m_can: Add hrtimer to generate software interrupt

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Message-ID: <31925752-8028-98fc-b6a4-9b8fe8a3ce0b@ti.com>
Date:   Mon, 22 May 2023 14:00:04 -0500
From:   Judith Mendez <jm@...com>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
CC:     Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        <linux-can@...r.kernel.org>,
        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>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Schuyler Patton <spatton@...com>,
        Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH v6 2/2] can: m_can: Add hrtimer to generate software
 interrupt

Hello,

On 5/22/23 1:37 PM, Marc Kleine-Budde wrote:
> On 22.05.2023 10:17:38, Judith Mendez wrote:
>>>> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
>>>> index 94dc82644113..3e60cebd9d12 100644
>>>> --- a/drivers/net/can/m_can/m_can_platform.c
>>>> +++ b/drivers/net/can/m_can/m_can_platform.c
>>>> @@ -5,6 +5,7 @@
>>>>    //
>>>>    // Copyright (C) 2018-19 Texas Instruments Incorporated - http://www.ti.com/
>>>> +#include <linux/hrtimer.h>
>>>>    #include <linux/phy/phy.h>
>>>>    #include <linux/platform_device.h>
>>>> @@ -96,12 +97,40 @@ static int m_can_plat_probe(struct platform_device *pdev)
>>>>    		goto probe_fail;
>>>>    	addr = devm_platform_ioremap_resource_byname(pdev, "m_can");
>>>> -	irq = platform_get_irq_byname(pdev, "int0");
>>>> -	if (IS_ERR(addr) || irq < 0) {
>>>> -		ret = -EINVAL;
>>>> +	if (IS_ERR(addr)) {
>>>> +		ret = PTR_ERR(addr);
>>>>    		goto probe_fail;
>>>>    	}
>>>
>>> As we don't use an explicit "poll-interval" anymore, this needs some
>>> cleanup. The flow should be (pseudo code, error handling omitted):
>>>
>>> if (device_property_present("interrupts") {
>>>           platform_get_irq_byname();
>>>           polling = false;
>>> } else {
>>>           hrtimer_init();
>>>           polling = true;
>>> }
>>
>> Ok.
>>
>>>
>>>> +	irq = platform_get_irq_byname_optional(pdev, "int0");
>>>
>>> Remove the "_optional" and....
>>
>> On V2, you asked to add the _optional?.....
>>
>>>   	irq = platform_get_irq_byname(pdev, "int0");
>>
>> use platform_get_irq_byname_optional(), it doesn't print an error
>> message.
> 
> ACK - I said that back in v2, when there was "poll-interval". But now we
> don't use "poll-interval" anymore, but test if interrupt properties are
> present.
> 
> See again pseudo-code I posted in my last mail:
> 
> | if (device_property_present("interrupts") {
> |          platform_get_irq_byname();
> 
> If this throws an error, it's fatal, bail out.
> 
> |          polling = false;
> | } else {
> |          hrtimer_init();
> |          polling = true;
> | }
> 

Ok, will add this then..


>>
>>>
>>>> +	if (irq == -EPROBE_DEFER) {
>>>> +		ret = -EPROBE_DEFER;
>>>> +		goto probe_fail;
>>>> +	}
>>>> +
>>>> +	if (device_property_present(mcan_class->dev, "interrupts") ||
>>>> +	    device_property_present(mcan_class->dev, "interrupt-names"))
>>>> +		mcan_class->polling = false;
>>>
>>> ...move the platform_get_irq_byname() here
>>
>> ok,
>>
>>>
>>>> +	else
>>>> +		mcan_class->polling = true;
>>>> +
>>>> +	if (!mcan_class->polling && irq < 0) {
>>>> +		ret = -ENXIO;
>>>> +		dev_err_probe(mcan_class->dev, ret, "IRQ int0 not found, polling not activated\n");
>>>> +		goto probe_fail;
>>>> +	}
>>>
>>> Remove this check.
>>
>> Should we not go to 'probe fail' if polling is not activated and irq is not
>> found?
> 
> If an interrupt property is present in the DT, we use it - if request
> IRQ fails, something is broken and we've already bailed out. See above.
> If there is no interrupt property we use polling.

Got it, thanks.

>>
>>>
>>>> +
>>>> +	if (mcan_class->polling) {
>>>> +		if (irq > 0) {
>>>> +			mcan_class->polling = false;
>>>> +			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");
>>>
>>> Remove this.
>>
>> Remove the dev_info?
> 
> ACK, this is not possible anymore - we cannot have polling enabled and
> HW IRQs configured.

Sounds good, will submit a v7 with these cleanup changes.

regards,
Judith