linux-kernel - Re: [PATCH] drivers: watchdog: rdc321x

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Date:   Fri, 7 Aug 2020 21:58:52 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Florian Fainelli <f.fainelli@...il.com>,
        madhuparnabhowmik10@...il.com
Cc:     wim@...ux-watchdog.org, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org, andrianov@...ras.ru,
        ldv-project@...uxtesting.org
Subject: Re: [PATCH] drivers: watchdog: rdc321x_wdt: Fix race condition bugs

[ ... ]
> The R8610-G datasheet is the one that I have had and used thus far.
> 

Mine is draft version 0.2. Do you have a newer version, by any chance ?

>> Unfortunately, none of those
>> describes the use of bit(31) in the watchdog register, nor the meaning
>> of bit(12) and bit(13). Bit(31) is described in the code as "Mask",
>> and it is set by a couple of commands. I _suspect_ that bit(31) has to be
>> set to change some of the register bits, for example the counter value.
>> That is just a wild guess, but it would explain why the driver works
>> in the first place.
>>
>> It is also not clear if the bits in the counter register are accumulative
>> or if only the highest bit counts. The datasheets suggest that only the
>> highest bit counts, but then the value of RDC_CLS_TMR doesn't make much
>> sense since it sets two bits.
>>
>> Since you wrote the driver, I was hoping that you might have a datasheet
>> which explains all this in more detail.
> 
> I do not, and this was over 12 years ago, and I honestly do not recall
> all the details, when I get the board running a newish kernel, I will
> poke around.
> 
Surprise :-)

Thanks,
Guenter