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Date: Wed, 26 Apr 2023 11:11:12 -0500
From: "Mendez, Judith" <jm@...com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
CC: Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
Wolfgang Grandegger <wg@...ndegger.com>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, <linux-can@...r.kernel.org>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Schuyler Patton <spatton@...com>, Nishanth Menon <nm@...com>,
Vignesh Raghavendra <vigneshr@...com>,
Tero Kristo <kristo@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<devicetree@...r.kernel.org>,
Oliver Hartkopp <socketcan@...tkopp.net>
Subject: Re: [PATCH v2 1/4] can: m_can: Add hrtimer to generate software
interrupt
Hello Marc,
On 4/24/2023 3:14 PM, Marc Kleine-Budde wrote:
> On 24.04.2023 14:53:59, 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@...com>
>> ---
>> Changelog:
>> v2:
>> 1. Add poll-interval to MCAN class device to check if poll-interval propery is
>> present in MCAN node, this enables timer polling method.
>> 2. Add 'polling' flag to MCAN class device to check if a device is using timer
>> polling method
>> 3. Check if both timer polling and hardware interrupt are enabled for a MCAN
>> device, default to hardware interrupt mode if both are enabled.
>> 4. Changed ms_to_ktime() to ns_to_ktime()
>> 5. Removed newlines, tabs, and restructure if/else section.
>>
>> drivers/net/can/m_can/m_can.c | 30 ++++++++++++++++++++-----
>> drivers/net/can/m_can/m_can.h | 5 +++++
>> drivers/net/can/m_can/m_can_platform.c | 31 ++++++++++++++++++++++++--
>> 3 files changed, 59 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
>> index a5003435802b..33e094f88da1 100644
>> --- a/drivers/net/can/m_can/m_can.c
>> +++ b/drivers/net/can/m_can/m_can.c
>> @@ -23,6 +23,7 @@
>> #include <linux/pinctrl/consumer.h>
>> #include <linux/platform_device.h>
>> #include <linux/pm_runtime.h>
>> +#include <linux/hrtimer.h>
>
> keep the list of includes sorted
>
Will do.
>>
>> #include "m_can.h"
>>
>> @@ -1587,6 +1588,11 @@ static int m_can_close(struct net_device *dev)
>> if (!cdev->is_peripheral)
>> napi_disable(&cdev->napi);
>>
>> + if (cdev->polling) {
>> + dev_dbg(cdev->dev, "Disabling the hrtimer\n");
>> + hrtimer_cancel(&cdev->hrtimer);
>> + }
>> +
>> m_can_stop(dev);
>> m_can_clk_stop(cdev);
>> free_irq(dev->irq, dev);
>> @@ -1793,6 +1799,18 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
>> return NETDEV_TX_OK;
>> }
>>
>> +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(1));
>
> Please create a define for this
>
Thanks, will create a define for the 1 ms polling interval.
>> +
>> + return HRTIMER_RESTART;
>> +}
>> +
>> static int m_can_open(struct net_device *dev)
>> {
>> struct m_can_classdev *cdev = netdev_priv(dev);
>> @@ -1827,13 +1845,15 @@ static int m_can_open(struct net_device *dev)
>> }
>>
>> INIT_WORK(&cdev->tx_work, m_can_tx_work_queue);
>> -
>> err = request_threaded_irq(dev->irq, NULL, m_can_isr,
>> - IRQF_ONESHOT,
>> - dev->name, dev);
>> - } else {
>> - err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
>> + IRQF_ONESHOT, dev->name, dev);
>> + } else if (!cdev->polling) {
>> + err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
>> dev);
>
> No need to change the indention
>
Will fix.
>> + } else {
>> + dev_dbg(cdev->dev, "Start hrtimer\n");
>> + cdev->hrtimer.function = &hrtimer_callback;
>> + hrtimer_start(&cdev->hrtimer, ms_to_ktime(cdev->poll_interval), HRTIMER_MODE_REL_PINNED);
>> }
>>
>> 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..1ba87eb23f8e 100644
>> --- a/drivers/net/can/m_can/m_can.h
>> +++ b/drivers/net/can/m_can/m_can.h
>> @@ -28,6 +28,7 @@
>> #include <linux/pm_runtime.h>
>> #include <linux/slab.h>
>> #include <linux/uaccess.h>
>> +#include <linux/hrtimer.h>
>
> keep the list of includes sorted
>
>>
>> /* m_can lec values */
>> enum m_can_lec_type {
>> @@ -93,6 +94,10 @@ struct m_can_classdev {
>> int is_peripheral;
>>
>> struct mram_cfg mcfg[MRAM_CFG_NUM];
>> +
>> + struct hrtimer hrtimer;
>> + u32 poll_interval;
>> + u8 polling;
>
> bool
>
Will use bool instead.
>> };
>>
>> 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 9c1dcf838006..e899c04edc01 100644
>> --- a/drivers/net/can/m_can/m_can_platform.c
>> +++ b/drivers/net/can/m_can/m_can_platform.c
>> @@ -7,6 +7,7 @@
>>
>> #include <linux/phy/phy.h>
>> #include <linux/platform_device.h>
>> +#include <linux/hrtimer.h>
>>
>> #include "m_can.h"
>>
>> @@ -97,11 +98,37 @@ static int m_can_plat_probe(struct platform_device *pdev)
>>
>> addr = devm_platform_ioremap_resource_byname(pdev, "m_can");
>> irq = platform_get_irq_byname(pdev, "int0");
>
> use platform_get_irq_byname_optional(), it doesn't print an error
> message.
>
Thanks.
>> - if (IS_ERR(addr) || irq < 0) {
>> - ret = -EINVAL;
>> + if (irq == -EPROBE_DEFER) {
>> + ret = -EPROBE_DEFER;
>> goto probe_fail;
>> }
>>
>> + if (IS_ERR(addr)) {
>> + ret = PTR_ERR(addr);
>> + goto probe_fail;
>> + }
>
> please move the error check for "addr" directly after the "addr = "
> assignment.
>
Will do.
>> +
>> + mcan_class->polling = 0;
>
> No need to init as "0"
>
Awsome thanks.
>> + if (device_property_present(mcan_class->dev, "poll-interval")) {
>> + mcan_class->polling = 1;
>> + }
>
> No need for the { } here.
>
>> +
>> + if (!mcan_class->polling && irq < 0) {
>> + ret = -ENODATA;
> -ENXIO
>> + dev_dbg(mcan_class->dev, "Polling not enabled\n");
>
> print a proper error message using dev_err_probe("IRQ %s not found and
> polling not activated\n")
>
Why %s when MCAN requests 1 IRQ which is "int0"? If we want to print
"int0", should it be hardcoded into the print error message?
>> + goto probe_fail;
>> + }
>> +
>> + if (mcan_class->polling && irq > 0) {
>> + mcan_class->polling = 0;
>> + dev_dbg(mcan_class->dev, "Polling not enabled, hardware interrupt exists\n");
>> + }
>> +
>> + if (mcan_class->polling && irq < 0) {
>> + dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
>> + hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
>> + }
>
> combine both if (mcan_class->polling) into one.
>
Will do.
>> +
>> /* message ram could be shared */
>> res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
>> if (!res) {
>> --
>> 2.17.1
>>
>>
regards,
Judith
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