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Date: Fri, 26 Apr 2019 13:17:19 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Anson Huang <anson.huang@....com>
Cc: "shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>,
"wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
Aisheng Dong <aisheng.dong@....com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 2/2] watchdog: imx_sc: Add pretimeout support
On Thu, Apr 25, 2019 at 05:44:45AM +0000, Anson Huang wrote:
> Hi, Guenter
>
> > -----Original Message-----
> > From: Guenter Roeck [mailto:groeck7@...il.com] On Behalf Of Guenter
> > Roeck
> > Sent: Thursday, April 25, 2019 12:04 PM
> > To: Anson Huang <anson.huang@....com>; shawnguo@...nel.org;
> > s.hauer@...gutronix.de; kernel@...gutronix.de; festevam@...il.com;
> > wim@...ux-watchdog.org; Aisheng Dong <aisheng.dong@....com>; linux-
> > arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; linux-
> > watchdog@...r.kernel.org
> > Cc: dl-linux-imx <linux-imx@....com>
> > Subject: Re: [PATCH 2/2] watchdog: imx_sc: Add pretimeout support
> >
> > On 4/24/19 6:14 PM, Anson Huang wrote:
> > > i.MX system controller watchdog can support pretimeout IRQ via general
> > > SCU MU IRQ, it depends on IMX_SCU and driver MUST be probed after SCU
> > > IPC ready, then enable corresponding SCU IRQ group and register SCU
> > > IRQ notifier, when watchdog pretimeout IRQ fires, SCU MU IRQ will be
> > > handled and watchdog pretimeout notifier will be called to handle the
> > > event.
> > >
> >
> > Ah, here is the missing patch.
> >
> > As mentioned in my other reply, the watchdog driver does now depend on
> > the SCU IPC handle and should be instantiated accordingly.
> > Using -EPROBE_DEFER to work around bad dependencies is not a solution.
>
> So, I have to move the i.MX system controller watchdog node into the i.MX SCU
> node in DT file now? As it depends on i.MX SCU firmware. If so, should I remove the
Yes, that is what I would suggest.
> previous i.MX system controller binding doc (fsl-imx-sc-wdt.txt) and add binding doc
> to (Documentation/devicetree/bindings/arm/freescale/fsl,scu.txt) ?
>
I can't comment on that; I am neutral on how the documentation is
handled.
> >
> > Additional comment below.
> >
> > Guenter
> >
> > > Signed-off-by: Anson Huang <Anson.Huang@....com>
> > > ---
> > > drivers/watchdog/Kconfig | 1 +
> > > drivers/watchdog/imx_sc_wdt.c | 65
> > +++++++++++++++++++++++++++++++++++++++----
> > > 2 files changed, 61 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > > 44a3158..f2c2c1a 100644
> > > --- a/drivers/watchdog/Kconfig
> > > +++ b/drivers/watchdog/Kconfig
> > > @@ -644,6 +644,7 @@ config IMX2_WDT
> > > config IMX_SC_WDT
> > > tristate "IMX SC Watchdog"
> > > depends on HAVE_ARM_SMCCC
> > > + depends on IMX_SCU
> > > select WATCHDOG_CORE
> > > help
> > > This is the driver for the system controller watchdog diff --git
> > > a/drivers/watchdog/imx_sc_wdt.c b/drivers/watchdog/imx_sc_wdt.c index
> > > 49848b6..f45ed10 100644
> > > --- a/drivers/watchdog/imx_sc_wdt.c
> > > +++ b/drivers/watchdog/imx_sc_wdt.c
> > > @@ -4,6 +4,7 @@
> > > */
> > >
> > > #include <linux/arm-smccc.h>
> > > +#include <linux/firmware/imx/sci.h>
> > > #include <linux/io.h>
> > > #include <linux/init.h>
> > > #include <linux/kernel.h>
> > > @@ -33,11 +34,16 @@
> > >
> > > #define SC_TIMER_WDOG_ACTION_PARTITION 0
> > >
> > > +#define SC_IRQ_WDOG 1
> > > +#define SC_IRQ_GROUP_WDOG 1
> > > +
> > > static bool nowayout = WATCHDOG_NOWAYOUT;
> > > module_param(nowayout, bool, 0000);
> > > MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once
> > started (default="
> > > __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> > >
> > > +struct watchdog_device *imx_sc_wdd;
> > > +
> > > static int imx_sc_wdt_ping(struct watchdog_device *wdog)
> > > {
> > > struct arm_smccc_res res;
> > > @@ -85,12 +91,42 @@ static int imx_sc_wdt_set_timeout(struct
> > watchdog_device *wdog,
> > > return res.a0 ? -EACCES : 0;
> > > }
> > >
> > > +static int imx_sc_wdt_set_pretimeout(struct watchdog_device *wdog,
> > > + unsigned int pretimeout)
> > > +{
> > > + struct arm_smccc_res res;
> > > +
> > > + wdog->pretimeout = pretimeout;
> > > + arm_smccc_smc(IMX_SIP_TIMER,
> > IMX_SIP_TIMER_SET_PRETIME_WDOG,
> > > + pretimeout * 1000, 0, 0, 0, 0, 0, &res);
> > > +
> > > + return res.a0 ? -EACCES : 0;
> >
> > If this function returns an error, why does it set wdog->pretimeout
> > unconditionally ? That seems wrong.
>
> You are right, I will fix it in V2, but looks like some other watchdog drivers also has such issue, such
> as below:
>
> drivers/watchdog/pm8916_wdt.c
> drivers/watchdog/sprd_wdt.c
>
You are correct, but that doesn't make this one better.
> >
> > > +}
> > > +
> > > +static int imx_sc_wdt_notify(struct notifier_block *nb,
> > > + unsigned long event, void *group) {
> > > + /* ignore other irqs */
> > > + if (!(event & SC_IRQ_WDOG &&
> > > + (*(u8 *)group == SC_IRQ_GROUP_WDOG)))
> >
> > if (!(event & SC_IRQ_WDO) || *(u8 *)group !=
> > SC_IRQ_GROUP_WDOG)
> >
> > would be easier to understand. Either case, the second part of the
> > expression has an unnecessary (), and multi-line alignment seems to be off.
>
> Will improve it and fix the line alignment in V2.
>
> >
> > > + return 0;
> > > +
> > > + watchdog_notify_pretimeout(imx_sc_wdd);
> >
> > The notifier block should be embedded in a local data structure, which would
> > include strict watchdog_device and struct notifier_block.
> > This would avoid the need for a static variable.
>
> OK, I will add a local data structure to do it in V2.
>
> >
> > > +
> > > + return 0;
> >
> > If the function always returns 0, why not the following ?
> > Above code seems unnecessary complex for no good reason.
> >
> > if (event & SC_IRQ_WDOG &&
> > *(u8 *)group == SC_IRQ_GROUP_WDOG)
> > watchdog_notify_pretimeout(imx_sc_wdd);
> >
> > return 0;
>
> OK.
>
> >
> > > +}
> > > +
> > > +static struct notifier_block imx_sc_wdt_notifier = {
> > > + .notifier_call = imx_sc_wdt_notify,
> > > +};
> > > +
> > > static const struct watchdog_ops imx_sc_wdt_ops = {
> > > .owner = THIS_MODULE,
> > > .start = imx_sc_wdt_start,
> > > .stop = imx_sc_wdt_stop,
> > > .ping = imx_sc_wdt_ping,
> > > .set_timeout = imx_sc_wdt_set_timeout,
> > > + .set_pretimeout = imx_sc_wdt_set_pretimeout,
> > > };
> > >
> > > static const struct watchdog_info imx_sc_wdt_info = { @@ -102,9
> > > +138,15 @@ static const struct watchdog_info imx_sc_wdt_info = {
> > > static int imx_sc_wdt_probe(struct platform_device *pdev)
> > > {
> > > struct device *dev = &pdev->dev;
> > > - struct watchdog_device *imx_sc_wdd;
> > > int ret;
> > >
> > > + /* wait until i.MX SCU IPC ready */
> > > + ret = imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> > > + SC_IRQ_WDOG,
> > > + true);
> > > + if (ret == -EPROBE_DEFER)
> > > + return ret;
> > > +
> >
> > And if the error is anything else it is ignored ?
> > Also, what happens if the interrupt triggers before imx_sc_wdd is set ?
>
> Other error ONLY means the IPC failed, the IRQ WDOG group will NOT be enabled,
> it does NOT impact other wdog functions, so I did NOT handle it, maybe I can add
> some warning message to tell user that pretimeout function is failed if other error
> occurs and also disable the pretimeout function in wdog info?
>
Something like that, yes.
> If interrupt triggers before imx_sc_wdd is set, since the notifier is NOT registered yet,
> so the wdog interrupt will be ignored.
>
> >
> > > imx_sc_wdd = devm_kzalloc(dev, sizeof(*imx_sc_wdd), GFP_KERNEL);
> > > if (!imx_sc_wdd)
> > > return -ENOMEM;
> > > @@ -117,6 +159,7 @@ static int imx_sc_wdt_probe(struct platform_device
> > *pdev)
> > > imx_sc_wdd->max_timeout = MAX_TIMEOUT;
> > > imx_sc_wdd->parent = dev;
> > > imx_sc_wdd->timeout = DEFAULT_TIMEOUT;
> > > + imx_sc_wdd->pretimeout = 0;
> >
> > Unnecessary.
>
> OK.
>
> >
> > >
> > > watchdog_init_timeout(imx_sc_wdd, 0, dev);
> > > watchdog_stop_on_reboot(imx_sc_wdd);
> > > @@ -128,13 +171,26 @@ static int imx_sc_wdt_probe(struct
> > platform_device *pdev)
> > > return ret;
> > > }
> > >
> > > + ret = imx_scu_irq_register_notifier(&imx_sc_wdt_notifier);
> > > + if (ret)
> > > + dev_warn(&pdev->dev,
> > > + "Failed to register watchdog irq notifier\n");
> >
> > pretimeout support doesn't work in this case, and any claim to support it
> > seems inappropriate.
>
> So how to disable pretimeout function in this case, just overwrite the watchdog_info
> to remove the WDIOF_PRETIMEOUT?
>
Yes, though I don't recall seeing WDIOF_PRETIMEOUT to start with.
Guenter
> >
> > > +
> > > return 0;
> > > }
> > >
> > > -static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
> > > +static int imx_sc_wdt_remove(struct platform_device *pdev)
> > > {
> > > - struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> > > + imx_scu_irq_unregister_notifier(&imx_sc_wdt_notifier);
> > > + imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> > > + SC_IRQ_WDOG,
> > > + false);
> > >
> > I would prefer to see devm_add_action() calls.
>
> Ah, agreed, will do it in V2.
>
> Thanks,
> Anson.
>
> >
> > > + return 0;
> > > +}
> > > +
> > > +static int __maybe_unused imx_sc_wdt_suspend(struct device *dev) {
> > > if (watchdog_active(imx_sc_wdd))
> > > imx_sc_wdt_stop(imx_sc_wdd);
> > >
> > > @@ -143,8 +199,6 @@ static int __maybe_unused
> > > imx_sc_wdt_suspend(struct device *dev)
> > >
> > > static int __maybe_unused imx_sc_wdt_resume(struct device *dev)
> > > {
> > > - struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> > > -
> > > if (watchdog_active(imx_sc_wdd))
> > > imx_sc_wdt_start(imx_sc_wdd);
> > >
> > > @@ -162,6 +216,7 @@ MODULE_DEVICE_TABLE(of, imx_sc_wdt_dt_ids);
> > >
> > > static struct platform_driver imx_sc_wdt_driver = {
> > > .probe = imx_sc_wdt_probe,
> > > + .remove = imx_sc_wdt_remove,
> > > .driver = {
> > > .name = "imx-sc-wdt",
> > > .of_match_table = imx_sc_wdt_dt_ids,
> > >
>
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