Re: [RFC 0/5] r8a7790: lager: add support for RCLK watchdog

[Wolfram Sang <wsa@the-dreams.de>]

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Geert,

> Thanks for your series!

And thanks for your input!

> no avail. Hence I went with the DA9063 instead. Note that I plan to look into
> the DA9063 interrupt storm issue soon.

Cool.

> I've just tried your series on Koelsch, and it suffers from the same problem.
> Does it work on Lager for both CONFIG_SMP=y and CONFIG_SMP=n?

I didn't. And what a surprise, it fails with SMP=y :( I'll having a
look...

> From the limited information available about the SWDT, it may be compatible
> with the RWDT. Or not. U-Boot disables both the RWDT and the SWDT on startup,
> using identical operations.

Well, the block diagram looks the same, the register layout in U-Boot
looks the same. And the bits I use are easy to be verified once I know
the IP core is there. Good enough, I'd say. And maybe we get
confirmation from the HW team via Morimoto-san.

> The RWDT exists on various shmobile SoCs.
> From digging into the datasheets, I had discovered two variants:
>   1. 32-bit registers
>        a. R-Car Gen2: using RST for restarting
>        b. R-Mobile APE6: using SYSC for restarting

Those should be handled with this driver.

>   2. 8-bit registers (SH-Mobile AP4/AG5, R-Mobile A1)
> 
> The differences are small: the variant with 8-bit registers has a smaller
> maximum timeout, and no magic value to be stored in the upper bits.

Do they also have 32kHz as input clock? Then they do need a ping every
8ms! Those should use the shwdt driver then which pings the device
frequently and runs a software watchdog on top to cope with the usual
watchdog granularity which is in the second range.

Thanks,

   Wolfram


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