linux-kernel - Re: [PATCH RFC v3 1/5] regulator: move monitor handling into own function

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Date:   Tue, 23 May 2023 12:46:39 +0300
From:   Matti Vaittinen <mazziesaccount@...il.com>
To:     Benjamin Bara <bbara93@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     support.opensource@...semi.com,
        DLG-Adam.Ward.opensource@...renesas.com,
        linux-kernel@...r.kernel.org,
        Benjamin Bara <benjamin.bara@...data.com>
Subject: Re: [PATCH RFC v3 1/5] regulator: move monitor handling into own
 function

Hi Benjamin,

Thanks for working on this. :)

On 5/21/23 14:39, Benjamin Bara wrote:
> From: Benjamin Bara <benjamin.bara@...data.com>
> 
> Similar to the existing implementation, the new function does not handle
> EOPNOTSUPP as an error. The initial monitoring state is set to the
> regulator state.

As far as I see, this changes the existing logic. Previously the 
monitoring was unconditionally enabled for all regulators, now it gets 
only enabled for regulators which are marked as enabled.

Furthermore, if I am not reading this wrong, the code tries to disable 
all protections if regulator is not enabled at startup(?)

I am not saying this is wrong. I am just saying that things will change 
here and likely to break something.

There are PMICs like ROHM BD9576, where the protection can not be disabled.

For example, the bd9576_set_uvp() has:
         if (severity == REGULATOR_SEVERITY_PROT) {
                 if (!enable || lim_uV)
                         return -EINVAL;
                 return 0;
         }

I am unsure if we might also have cases where some regulator could 
really be enabled w/o core knowing it. There can also be a problem if we 
have hardware where monitoring is common for all regulators, eg either 
globally enabled / disabled.

Yours,
	-- Matti

-- 
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~