From: Tero Kristo <t-kristo@ti.com>
To: Jan Kiszka <jan.kiszka@siemens.com>, <wim@linux-watchdog.org>,
<linux@roeck-us.net>, <linux-watchdog@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] watchdog: rti: tweak min_hw_heartbeat_ms to match initial allowed window
Date: Thu, 25 Jun 2020 11:32:07 +0300 [thread overview]
Message-ID: <b3849bea-2a4d-079e-e9df-8a1d6c13c0c7@ti.com> (raw)
In-Reply-To: <289c6104-a885-d3c1-c670-a081ebaaf782@siemens.com>
On 24/06/2020 18:24, Jan Kiszka wrote:
> On 24.06.20 13:45, Tero Kristo wrote:
>> If the RTI watchdog has been started by someone (like bootloader) when
>> the driver probes, we must adjust the initial ping timeout to match the
>> currently running watchdog window to avoid generating watchdog reset.
>>
>> Signed-off-by: Tero Kristo <t-kristo@ti.com>
>> ---
>> drivers/watchdog/rti_wdt.c | 25 +++++++++++++++++++++++++
>> 1 file changed, 25 insertions(+)
>>
>> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
>> index d456dd72d99a..02ea2b2435f5 100644
>> --- a/drivers/watchdog/rti_wdt.c
>> +++ b/drivers/watchdog/rti_wdt.c
>> @@ -55,11 +55,13 @@ static int heartbeat;
>> * @base - base io address of WD device
>> * @freq - source clock frequency of WDT
>> * @wdd - hold watchdog device as is in WDT core
>> + * @min_hw_heartbeat_save - save of the min hw heartbeat value
>> */
>> struct rti_wdt_device {
>> void __iomem *base;
>> unsigned long freq;
>> struct watchdog_device wdd;
>> + unsigned int min_hw_heartbeat_save;
>> };
>> static int rti_wdt_start(struct watchdog_device *wdd)
>> @@ -107,6 +109,11 @@ static int rti_wdt_ping(struct watchdog_device *wdd)
>> /* put watchdog in active state */
>> writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
>> + if (wdt->min_hw_heartbeat_save) {
>> + wdd->min_hw_heartbeat_ms = wdt->min_hw_heartbeat_save;
>> + wdt->min_hw_heartbeat_save = 0;
>> + }
>> +
>> return 0;
>> }
>> @@ -201,6 +208,24 @@ static int rti_wdt_probe(struct platform_device
>> *pdev)
>> goto err_iomap;
>> }
>> + if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
>> + u32 time_left;
>> + u32 heartbeat;
>> +
>> + set_bit(WDOG_HW_RUNNING, &wdd->status);
>> + time_left = rti_wdt_get_timeleft(wdd);
>> + heartbeat = readl(wdt->base + RTIDWDPRLD);
>> + heartbeat <<= WDT_PRELOAD_SHIFT;
>> + heartbeat /= wdt->freq;
>> + if (time_left < heartbeat / 2)
>> + wdd->min_hw_heartbeat_ms = 0;
>> + else
>> + wdd->min_hw_heartbeat_ms =
>> + (time_left - heartbeat / 2 + 1) * 1000;
>> +
>> + wdt->min_hw_heartbeat_save = 11 * heartbeat * 1000 / 20;
>> + }
>> +
>> ret = watchdog_register_device(wdd);
>> if (ret) {
>> dev_err(dev, "cannot register watchdog device\n");
>>
>
> This assumes that the bootloader also programmed a 50% window, right?
> The pending U-Boot patch will do that, but what if that may chance or
> someone uses a different setup?
Yes, we assume 50%. I think based on the hw design, 50% is the only sane
value to be used, otherwise you just shrink the open window too much and
for no apparent reason.
-Tero
--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
next prev parent reply other threads:[~2020-06-25 8:32 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 11:45 [PATCH 0/2] watchdog: rti: adjust initial ping for attach Tero Kristo
2020-06-24 11:45 ` [PATCH 1/2] watchdog: use __watchdog_ping in startup Tero Kristo
2020-06-30 20:36 ` Guenter Roeck
2020-06-24 11:45 ` [PATCH 2/2] watchdog: rti: tweak min_hw_heartbeat_ms to match initial allowed window Tero Kristo
2020-06-24 15:24 ` Jan Kiszka
2020-06-25 8:32 ` Tero Kristo [this message]
2020-06-25 10:00 ` Jan Kiszka
2020-06-25 13:35 ` Guenter Roeck
2020-06-25 17:04 ` Tero Kristo
2020-06-30 20:23 ` Guenter Roeck
2020-07-01 5:50 ` Tero Kristo
2020-07-01 13:34 ` Guenter Roeck
2020-07-01 14:36 ` Tero Kristo
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