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Message-ID: <20230420-unlikable-overstep-6ad655c5bbdc-mkl@pengutronix.de>
Date: Thu, 20 Apr 2023 11:37:35 +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 1/4] can: m_can: Add hrtimer to generate software
interrupt
On 19.04.2023 17:33:20, Judith Mendez wrote:
> Add an hrtimer to MCAN struct. Each MCAN will have its own
> hrtimer instantiated if there is no hardware interrupt found.
>
> 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>
> ---
> drivers/net/can/m_can/m_can.c | 30 ++++++++++++++++++++++++--
> drivers/net/can/m_can/m_can.h | 3 +++
> drivers/net/can/m_can/m_can_platform.c | 13 +++++++++--
> 3 files changed, 42 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..8784bdea300a 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>
>
> #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 (dev->irq < 0) {
> + 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));
> +
> + return HRTIMER_RESTART;
> +}
> +
> static int m_can_open(struct net_device *dev)
> {
> struct m_can_classdev *cdev = netdev_priv(dev);
> @@ -1827,13 +1845,21 @@ 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);
> +
nitpick:
Please remove these 2 newline changes.
> } else {
> - err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
> + if (dev->irq > 0) {
Please follow the kernel coding style and use a space not a tab after
the closing ")" of the "if".
> + err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
> dev);
> + }
> +
> + else {
Please use kernel coding style: "} else {"
> + dev_dbg(cdev->dev, "Enabling the hrtimer\n");
> + cdev->hrtimer.function = &hrtimer_callback;
> + hrtimer_start(&cdev->hrtimer, ns_to_ktime(0), HRTIMER_MODE_REL_PINNED);
> + }
I think there's no need to have nested else branches, what about this
approach?
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1831,9 +1831,11 @@ 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 (dev->irq) {
err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
dev);
+ } else {
+ // polling
}
if (err < 0) {
> }
>
> 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..ed046d77fdb9 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>
>
> /* m_can lec values */
> enum m_can_lec_type {
> @@ -93,6 +94,8 @@ struct m_can_classdev {
> int is_peripheral;
>
> struct mram_cfg mcfg[MRAM_CFG_NUM];
> +
> + struct hrtimer hrtimer;
> };
>
> 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..7540db74b7d0 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"
>
> @@ -98,8 +99,16 @@ 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");
> if (IS_ERR(addr) || irq < 0) {
> - ret = -EINVAL;
> - goto probe_fail;
> + if (irq == -EPROBE_DEFER) {
> + ret = -EPROBE_DEFER;
> + goto probe_fail;
> + }
> + if (IS_ERR(addr)) {
> + ret = PTR_ERR(addr);
> + goto probe_fail;
> + }
> + dev_dbg(mcan_class->dev, "Failed to get irq, initialize hrtimer\n");
> + hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
Looks better. Please remove the outer "if (IS_ERR(addr) || irq < 0)" and
move the error checking directly after "addr = devm_platform_ioremap_resource_byname()".
What do you think about introducing the "poll-interval" property and
only enable polling if it is set?
> }
>
> /* message ram could be shared */
> --
> 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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