From: Evan Benn <evanbenn@chromium.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Julius Werner <jwerner@chromium.org>,
Xingyu Chen <xingyu.chen@amlogic.com>,
LKML <linux-kernel@vger.kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Anson Huang <Anson.Huang@nxp.com>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
"David S. Miller" <davem@davemloft.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Leonard Crestez <leonard.crestez@nxp.com>,
Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>,
Mark Rutland <mark.rutland@arm.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Olof Johansson <olof@lixom.net>, Rob Herring <robh+dt@kernel.org>,
Rob Herring <robh@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Vinod Koul <vkoul@kernel.org>, Will Deacon <will@kernel.org>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
devicetree@vger.kernel.org,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
LINUX-WATCHDOG <linux-watchdog@vger.kernel.org>,
Jianxin Pan <jianxin.pan@amlogic.com>,
Yonghui Yu <yonghui.yu@amlogic.com>,
"open list:ARM/Amlogic Meson..."
<linux-amlogic@lists.infradead.org>
Subject: Re: [PATCH v2 0/2] Add a watchdog driver that uses ARM Secure Monitor Calls.
Date: Thu, 16 Apr 2020 10:46:39 +1000 [thread overview]
Message-ID: <CAKz_xw0+gKBM1jp-Avnd+4j9vSxUix67RZBX-NNbStb0+ri4+Q@mail.gmail.com> (raw)
In-Reply-To: <20200415231215.GA182398@roeck-us.net>
Thanks Xingyu,
Can anyone provide advice about making SMCWD_FUNC_ID a device tree
param directly, vs using the compatible to select from a table.
Please note get_timeleft erroneously returns res.a0 instead of res.a1
in this version.
Evan
On Thu, Apr 16, 2020 at 9:12 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Wed, Apr 15, 2020 at 03:29:29PM -0700, Julius Werner wrote:
> > > In addition, It looks more reasonable to use the "msec" as the unit of
> > > timeout parameter for the ATF fw interface with SMCWD_SET_TIMEOUT:
> > >
> > > - The fw interface will compatible with the uboot generic watchdog
> > > interface at [0], and there is no need to convert timeout from msec
> > > to sec.
> >
> > I think we're trying hard to keep this compatible to a Trusted
> > Firmware counterpart that we have already shipped, so we would prefer
> > to keep it at seconds if possible. That's what the Linux watchdog core
> > uses as well after all, so it just seems natural. I don't really see
> > how what U-Boot does would have anything to do with this.
> >
> > > - Some vendor's watchdog may be not support the "wdt_trigger_reset"
> > > reset operation, but they can use the method below to reset the system
> > > by the watchdog right now.
> > >
> > > watchdog_set_time(1); //1ms
> > > watchdog_enable();
> >
> > They can still do that but they should do that on the Trusted Firmware
> > side. Emulating a missing reset functionality should be handled by the
> > hardware abstraction layer (in this case Trusted Firmware), not at the
> > Linux API level. So Linux would still send a PSCI_SYSTEM_RESET SMC,
> > but then Trusted Firmware can choose to implement that by setting the
> > watchdog to the smallest possible timeout (which it can because it's
> > accessing it directly, not through this SMC interface) and letting it
> > expire.
>
> I agree. Using a watchdog to implement reset functionality is always a
> means of last resort and should be avoided if possible.
>
> Guenter
next prev parent reply other threads:[~2020-04-16 0:52 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 5:28 [PATCH v2 0/2] Add a watchdog driver that uses ARM Secure Monitor Calls Evan Benn
2020-04-03 5:28 ` [PATCH v2 1/2] dt-bindings: watchdog: Add ARM smc wdt for mt8173 watchdog Evan Benn
2020-04-03 5:29 ` [PATCH v2 2/2] watchdog: Add new arm_smd_wdt watchdog driver Evan Benn
2020-04-03 6:00 ` Guenter Roeck
2020-04-03 22:56 ` Julius Werner
2020-04-04 1:00 ` Evan Benn
2020-04-03 6:08 ` [PATCH v2 0/2] Add a watchdog driver that uses ARM Secure Monitor Calls Evan Benn
[not found] ` <CAKz_xw0gV+w_gMkLfB4qUBdULLfFoiv1TBWp9_PHy33wP_XWyA@mail.gmail.com>
[not found] ` <890948ef-7276-fdae-d270-eb30eff3eab2@amlogic.com>
2020-04-15 11:54 ` Xingyu Chen
2020-04-15 22:29 ` Julius Werner
2020-04-15 23:12 ` Guenter Roeck
2020-04-16 0:46 ` Evan Benn [this message]
2020-04-16 0:56 ` Julius Werner
2020-04-16 3:48 ` Florian Fainelli
2020-04-21 1:08 ` Evan Benn
2020-04-21 2:36 ` Florian Fainelli
2020-04-16 3:23 ` Xingyu Chen
-- strict thread matches above, loose matches on Subject: below --
2020-04-21 11:05 Evan Benn
2020-04-21 14:32 ` Guenter Roeck
2020-04-22 0:40 ` Evan Benn
2020-02-21 5:38 Evan Benn
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