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Message-ID: <84e5b09e-f8b9-15ae-4871-e5e4c4f4a470@ti.com>
Date: Tue, 9 May 2023 17:18:06 -0500
From: Judith Mendez <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>,
Simon Horman <simon.horman@...igine.com>
Subject: Re: [PATCH v4 2/4] can: m_can: Add hrtimer to generate software
interrupt
Hello Marc,
On 5/2/23 01:37, Marc Kleine-Budde wrote:
> On 01.05.2023 17:46:22, 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>
>
> I think this patch is as good as it gets, given the HW and SW
> limitations of the coprocessor.
>
> Some minor nitpicks inline. No need to resend from my point of view,
> I'll fixup while applying the patch.
>
> Marc
>
>> ---
>> Changelog:
>> v1:
>> 1. Sort list of includes
>> 2. Create a define for HR_TIMER_POLL_INTERVAL
>> 3. Fix indentations and style issues/warnings
>> 4. Change polling variable to type bool
>> 5. Change platform_get_irq to optional so not to print error msg
>> 6. Move error check for addr directly after assignment
>> 7. Print appropriate error msg with dev_err_probe insead of dev_dbg
>>
>> 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. Change ms_to_ktime() to ns_to_ktime()
>> 5. Remove newlines, tabs, and restructure if/else section
>>
>> drivers/net/can/m_can/m_can.c | 29 +++++++++++++++++++++--
>> drivers/net/can/m_can/m_can.h | 4 ++++
>> drivers/net/can/m_can/m_can_platform.c | 32 +++++++++++++++++++++++---
>> 3 files changed, 60 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
>> index a5003435802b..e1ac0c1d85a3 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.
>> @@ -1587,6 +1591,11 @@ 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 +1802,18 @@ 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);
>> @@ -1827,13 +1848,17 @@ static int m_can_open(struct net_device *dev)
>> }
>>
>> INIT_WORK(&cdev->tx_work, m_can_tx_work_queue);
>> -
>
> unrelated change
>
>> 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 {
>> + dev_dbg(cdev->dev, "Start hrtimer\n");
>> + cdev->hrtimer.function = &hrtimer_callback;
>> + hrtimer_start(&cdev->hrtimer, ms_to_ktime(HRTIMER_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..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 9c1dcf838006..0fcb436298f8 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 +97,37 @@ 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, "poll-interval"))
>> + mcan_class->polling = 1;
>
> true
>
>> +
>> + if (!mcan_class->polling && irq < 0) {
>> + ret = -ENXIO;
>> + dev_err_probe(mcan_class->dev, ret, "IRQ int0 not found and polling not activated\n");
>> + goto probe_fail;
>> + }
>> +
>> + if (mcan_class->polling) {
>> + if (irq > 0) {
>> + mcan_class->polling = 0;
>
> false
>
>> + dev_dbg(mcan_class->dev, "Polling enabled and hardware IRQ found, use hardware IRQ\n");
>
> "...using hardware IRQ"
>
> Use dev_info(), as there is something not 100% correct with the DT.
Is it dev_info or dev_dbg? I used to have dev_info since it was nice to see when polling was
enabled. Also, I had seen this print and the next as informative prints, hence the dev_info().
However, I was told in this review process to change to dev_dbg. Which is correct?
>> + } 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
>>
>>
>
regards,
Judith
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