[PATCH v6 0/2] Enable multiple MCAN on AM62x

[PATCH v6 0/2] Enable multiple MCAN on AM62x

[Judith Mendez]

On AM62x there are two MCANs in MCU domain. The MCANs in MCU domain
were not enabled since there is no hardware interrupt routed to A53
GIC interrupt controller. Therefore A53 Linux cannot be interrupted
by MCU MCANs.

This solution instantiates a hrtimer with 1 ms polling interval
for MCAN device when there is no hardware interrupt property in
DTB MCAN node. The hrtimer generates a recurring software interrupt
which allows to call the isr. The isr will check if there is pending
transaction by reading a register and proceed normally if there is.
MCANs with hardware interrupt routed to A53 Linux will continue to
use the hardware interrupt as expected.

Timer polling method was tested on both classic CAN and CAN-FD
at 125 KBPS, 250 KBPS, 1 MBPS and 2.5 MBPS with 4 MBPS bitrate
switching.

Letency and CPU load benchmarks were tested on 3x MCAN on AM62x.
1 MBPS timer polling interval is the better timer polling interval
since it has comparable latency to hardware interrupt with the worse
case being 1ms + CAN frame propagation time and CPU load is not
substantial. Latency can be improved further with less than 1 ms
polling intervals, howerver it is at the cost of CPU usage since CPU
load increases at 0.5 ms.

Note that in terms of power, enabling MCU MCANs with timer-polling
implementation might have negative impact since we will have to wake
up every 1 ms whether there are CAN packets pending in the RX FIFO or
not. This might prevent the CPU from entering into deeper idle states
for extended periods of time.

v5:
Link: https://lore.kernel.org/linux-can/20230510202952.27111-1-jm@ti.com/T/#t

v4:
Link: https://lore.kernel.org/linux-can/c3395692-7dbf-19b2-bd3f-31ba86fa4ac9@linaro.org/T/#t

v2:
Link: https://lore.kernel.org/linux-can/20230424195402.516-1-jm@ti.com/T/#t

V1:
Link: https://lore.kernel.org/linux-can/19d8ae7f-7b74-a869-a818-93b74d106709@ti.com/T/#t

RFC:
Link: https://lore.kernel.org/linux-can/52a37e51-4143-9017-42ee-8d17c67028e3@ti.com/T/#t

v6:
- Move hrtimer stop/start function calls to m_can_open and m_can_close to
support power suspend/resume

v5:
- Remove poll-interval in bindings
- Change dev_dbg to dev_info if hardware int exists and polling
is enabled

v4:
- Wrong patches sent

v3:
- Update binding poll-interval description
- Add oneOf to select either interrupts/interrupt-names or poll-interval
- Create a define for 1 ms polling interval
- Change plarform_get_irq to optional to not print error msg

v2:
- Add poll-interval property to bindings and MCAN DTB node
- Add functionality to check for 'poll-interval' property in MCAN node 
- Bindings: add an example using poll-interval
- Add 'polling' flag in driver to check if device is using polling method
- Check for timer polling and hardware interrupt cases, default to
hardware interrupt method
- Change ns_to_ktime() to ms_to_ktime()

Judith Mendez (2):
  dt-bindings: net: can: Remove interrupt properties for MCAN
  can: m_can: Add hrtimer to generate software interrupt

 .../bindings/net/can/bosch,m_can.yaml         | 20 +++++++++--
 drivers/net/can/m_can/m_can.c                 | 31 +++++++++++++++-
 drivers/net/can/m_can/m_can.h                 |  4 +++
 drivers/net/can/m_can/m_can_platform.c        | 35 +++++++++++++++++--
 4 files changed, 84 insertions(+), 6 deletions(-)


base-commit: 798d276b39e984345d52b933a900a71fa0815928
-- 
2.17.1

[PATCH v6 1/2] dt-bindings: net: can: Remove interrupt properties for MCAN

[Judith Mendez]

On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
routed to A53 Linux, instead they will use software interrupt by
timer polling.

To enable timer polling method, interrupts should be
optional so remove interrupts property from required section and
add an example for MCAN node with timer polling enabled.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Judith Mendez <jm@ti.com>
---
Changelog:
v6:
   1. No changes
v5:
   1. Remove poll-interval
   2. Remove oneOf that selects interrupts/interrupt-names or poll-interval
v3:
   1. Update binding poll-interval description
   2. Add oneOf to select interrupts/interrupt-names or poll-interval
v2:
   1. Add poll-interval property to enable timer polling method
   2. Add example using poll-interval property
---
 .../bindings/net/can/bosch,m_can.yaml         | 20 +++++++++++++++++--
 1 file changed, 18 insertions(+), 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..bb518c831f7b 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
@@ -132,6 +130,7 @@ additionalProperties: false
 
 examples:
   - |
+    // Example with interrupts
     #include <dt-bindings/clock/imx6sx-clock.h>
     can@20e8000 {
       compatible = "bosch,m_can";
@@ -149,4 +148,21 @@ examples:
       };
     };
 
+  - |
+    // Example with timer polling
+    #include <dt-bindings/clock/imx6sx-clock.h>
+    can@20e8000 {
+      compatible = "bosch,m_can";
+      reg = <0x020e8000 0x4000>, <0x02298000 0x4000>;
+      reg-names = "m_can", "message_ram";
+      clocks = <&clks IMX6SX_CLK_CANFD>,
+               <&clks IMX6SX_CLK_CANFD>;
+      clock-names = "hclk", "cclk";
+      bosch,mram-cfg = <0x0 0 0 32 0 0 0 1>;
+
+      can-transceiver {
+        max-bitrate = <5000000>;
+      };
+    };
+
 ...
-- 
2.17.1

[PATCH v6 2/2] can: m_can: Add hrtimer to generate software interrupt

[Judith Mendez]

Add an hrtimer to MCAN class device. Each MCAN will have its own
hrtimer instantiated if there is no hardware interrupt found and
poll-interval property is defined in device tree M_CAN node.

The hrtimer will generate a software interrupt every 1 ms. In
hrtimer callback, we check if there is a transaction pending by
reading a register, then process by calling the isr if there is.

Signed-off-by: Judith Mendez <jm@ti.com>
---
Changelog:
v6:
- Move hrtimer stop/start function calls to m_can_open and m_can_close to
support power suspend/resume
v5:
- Change dev_dbg to dev_info if hardware interrupt exists and polling
is enabled
v4:
- No changes
v3:
- Create a define for 1 ms polling interval
- Change plarform_get_irq to optional to not print error msg
v2:
- Add functionality to check for 'poll-interval' property in MCAN node 
- Add 'polling' flag in driver to check if device is using polling method
- Check for timer polling and hardware interrupt cases, default to
hardware interrupt method
- Change ns_to_ktime() to ms_to_ktime()
---
 drivers/net/can/m_can/m_can.c          | 31 ++++++++++++++++++++++-
 drivers/net/can/m_can/m_can.h          |  4 +++
 drivers/net/can/m_can/m_can_platform.c | 35 +++++++++++++++++++++++---
 3 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index a5003435802b..cfb3e433c0dd 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -11,6 +11,7 @@
 #include <linux/bitfield.h>
 #include <linux/can/dev.h>
 #include <linux/ethtool.h>
+#include <linux/hrtimer.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
@@ -308,6 +309,9 @@ enum m_can_reg {
 #define TX_EVENT_MM_MASK	GENMASK(31, 24)
 #define TX_EVENT_TXTS_MASK	GENMASK(15, 0)
 
+/* Hrtimer polling interval */
+#define HRTIMER_POLL_INTERVAL		1
+
 /* The ID and DLC registers are adjacent in M_CAN FIFO memory,
  * and we can save a (potentially slow) bus round trip by combining
  * reads and writes to them.
@@ -1414,6 +1418,12 @@ static int m_can_start(struct net_device *dev)
 
 	m_can_enable_all_interrupts(cdev);
 
+	if (cdev->polling) {
+		dev_dbg(cdev->dev, "Start hrtimer\n");
+		hrtimer_start(&cdev->hrtimer, ms_to_ktime(HRTIMER_POLL_INTERVAL),
+			      HRTIMER_MODE_REL_PINNED);
+	}
+
 	return 0;
 }
 
@@ -1571,6 +1581,11 @@ static void m_can_stop(struct net_device *dev)
 	/* disable all interrupts */
 	m_can_disable_all_interrupts(cdev);
 
+	if (cdev->polling) {
+		dev_dbg(cdev->dev, "Disabling the hrtimer\n");
+		hrtimer_cancel(&cdev->hrtimer);
+	}
+
 	/* Set init mode to disengage from the network */
 	m_can_config_endisable(cdev, true);
 
@@ -1793,6 +1808,18 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 }
 
+static enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)
+{
+	struct m_can_classdev *cdev = container_of(timer, struct
+						   m_can_classdev, hrtimer);
+
+	m_can_isr(0, cdev->net);
+
+	hrtimer_forward_now(timer, ms_to_ktime(HRTIMER_POLL_INTERVAL));
+
+	return HRTIMER_RESTART;
+}
+
 static int m_can_open(struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
@@ -1831,9 +1858,11 @@ static int m_can_open(struct net_device *dev)
 		err = request_threaded_irq(dev->irq, NULL, m_can_isr,
 					   IRQF_ONESHOT,
 					   dev->name, dev);
-	} else {
+	} else if (!cdev->polling) {
 		err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
 				  dev);
+	} else {
+		cdev->hrtimer.function = &hrtimer_callback;
 	}
 
 	if (err < 0) {
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index a839dc71dc9b..e9db5cce4e68 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -15,6 +15,7 @@
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/freezer.h>
+#include <linux/hrtimer.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
@@ -93,6 +94,9 @@ struct m_can_classdev {
 	int is_peripheral;
 
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
+
+	struct hrtimer hrtimer;
+	bool polling;
 };
 
 struct m_can_classdev *m_can_class_allocate_dev(struct device *dev, int sizeof_priv);
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;
 	}
 
+	irq = platform_get_irq_byname_optional(pdev, "int0");
+	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;
+	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;
+	}
+
+	if (mcan_class->polling) {
+		if (irq > 0) {
+			mcan_class->polling = false;
+			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");
+		} else {
+			dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
+			hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC,
+				     HRTIMER_MODE_REL_PINNED);
+		}
+	}
+
 	/* message ram could be shared */
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
 	if (!res) {
-- 
2.17.1

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

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 3188 bytes --]

On 18.05.2023 14:36:13, Judith Mendez wrote:
> Add an hrtimer to MCAN class device. Each MCAN will have its own
> hrtimer instantiated if there is no hardware interrupt found and
> poll-interval property is defined in device tree M_CAN node.
> 
> The hrtimer will generate a software interrupt every 1 ms. In
> hrtimer callback, we check if there is a transaction pending by
> reading a register, then process by calling the isr if there is.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>

[...]

> 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;
}

> +	irq = platform_get_irq_byname_optional(pdev, "int0");

Remove the "_optional" and....

> +	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

> +	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.

> +
> +	if (mcan_class->polling) {
> +		if (irq > 0) {
> +			mcan_class->polling = false;
> +			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");

Remove this.

> +		} else {
> +			dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
> +			hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC,
> +				     HRTIMER_MODE_REL_PINNED);

move this backwards, where you set "polling = true"

> +		}
> +	}
> +
>  	/* message ram could be shared */
>  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
>  	if (!res) {
> -- 
> 2.17.1

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

[Judith Mendez]

Hello Marc,

On 5/19/23 2:16 AM, Marc Kleine-Budde wrote:
> On 18.05.2023 14:36:13, Judith Mendez wrote:
>> Add an hrtimer to MCAN class device. Each MCAN will have its own
>> hrtimer instantiated if there is no hardware interrupt found and
>> poll-interval property is defined in device tree M_CAN node.
>>
>> The hrtimer will generate a software interrupt every 1 ms. In
>> hrtimer callback, we check if there is a transaction pending by
>> reading a register, then process by calling the isr if there is.
>>
>> Signed-off-by: Judith Mendez <jm@ti.com>
> 
> [...]

Missed this poll-interval, thanks.

> 
>> 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.

> 
>> +	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 (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?

> 
>> +		} else {
>> +			dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
>> +			hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC,
>> +				     HRTIMER_MODE_REL_PINNED);
> 
> move this backwards, where you set "polling = true"

ok,
> 
>> +		}
>> +	}
>> +
>>   	/* message ram could be shared */
>>   	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
>>   	if (!res) {
>> -- 
>> 2.17.1

- judith

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

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 3663 bytes --]

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;
| }


> 
> > 
> > > +	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.

> 
> > 
> > > +
> > > +	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.

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

[Judith Mendez]

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