linux-kernel - RE: [RFC PATCH] watchdog: da9062: Correct the timeout values

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Message-ID: <46136729bb564aa6b9f332fa584b2575@dh-electronics.com>
Date:   Mon, 6 Dec 2021 07:47:51 +0000
From:   Christoph Niedermaier <cniedermaier@...electronics.com>
To:     Andrej Picej <andrej.picej@...ik.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>
CC:     Support Opensource <support.opensource@...semi.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Guenter Roeck <linux@...ck-us.net>
Subject: RE: [RFC PATCH] watchdog: da9062: Correct the timeout values

From: Andrej Picej
Sent: Monday, December 6, 2021 8:29 AM
>>>> I measured the timeout values of my DA9061 chip. According to the
>>>> information in the data sheet the formula should be:
>>>>
>>>> timeout = 2.048 * 2^(regval - 1)
>>>>
>>>> But my measured values differ from that.
>>>> Accoring to my measured values the formula must be:
>>>>
>>>> timeout = 3.2 * 2^(regval - 1)
>>>>
>>>> Is there something wrong with my chip, or has anyone else noticed this as well?
>>>
>>> The driver assumes a static and well defined clock rate. Maybe that rate
>>> is different in your system (if that is possible) ?
>>>
>>> Guenter
>>
>> @Andrej
>> Do the values in the driver match what your chip does?
>>
> 
> Just did a quick test. The values in the driver match what the chip
> does. I checked multiple timeouts 16, 32, 65 and 131 seconds. The
> timeout triggers quite accurately.
> 
>> I have not changed anything. After power on, the chip behaves like this.
>> So I guess it either come from an OTP value or the wiring outside the chip.
>> Does anyone know what needs to be checked?
> 
> Can't help you here, sorry.
> 

Thanks anyway, so now I know it must be
problem with my DA9061 chip.

@Adam
Where can it come from?
Can you give we a hint what to check?


Thanks and best regards
Christoph