From: Guenter Roeck <linux@roeck-us.net>
To: Shaokun Zhang <zhangshaokun@hisilicon.com>,
linux-watchdog@vger.kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>,
Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
Al Stone <al.stone@linaro.org>,
Jianchao Hu <hujianchao@hisilicon.com>,
Huiqiang Wang <wanghuiqiang@huawei.com>
Subject: Re: [PATCH] watchdog: sbsa: Support architecture version 1
Date: Mon, 10 May 2021 06:16:19 -0700 [thread overview]
Message-ID: <669e1175-2eee-6c4b-8524-c672626022b6@roeck-us.net> (raw)
In-Reply-To: <bf9e1b65-119b-d027-fc3d-8491cbc38cde@hisilicon.com>
On 5/10/21 1:25 AM, Shaokun Zhang wrote:
> Hi Guenter,
>
> On 2021/5/10 12:25, Guenter Roeck wrote:
>> On 5/9/21 8:41 PM, Shaokun Zhang wrote:
>>> Arm Base System Architecture 1.0[1] has introduced watchdog
>>> revision 1 that increases the length the watchdog offset
>>
>> Is that how they call the watchdog count register ?
>>
>
> I think yes.
>
>> Also, doesn't that mean that the maximum timeout supported
>> by the hardware is now larger ?
>
> No, maximum timeout is the same. But the clock can be higher than
> before. For Armv8.6, The frequency of CNTFRQ_EL0 is standardized to
> a frequency of 1GHz which will set gwdt->clk. If the timeout is
> greater than 4(second), the 32-bit counter(WOR) is not enough.
>
The maximuma timeout is limited with
wdd->max_hw_heartbeat_ms = U32_MAX / gwdt->clk * 1000;
You did not update that calculation. That means that the maximuma
timeout is still U32_MAX / gwdt->clk * 1000, which still fits
into 32 bit.
Please correct me if I am missing something.
Guenter
next prev parent reply other threads:[~2021-05-10 13:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 3:41 [PATCH] watchdog: sbsa: Support architecture version 1 Shaokun Zhang
2021-05-10 4:25 ` Guenter Roeck
2021-05-10 8:25 ` Shaokun Zhang
2021-05-10 8:44 ` Shaokun Zhang
2021-05-10 15:23 ` Guenter Roeck
2021-05-10 13:16 ` Guenter Roeck [this message]
2021-05-11 2:49 ` Shaokun Zhang
2021-05-11 3:52 ` Guenter Roeck
2021-05-11 6:03 ` Shaokun Zhang
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