linux-kernel - Re: [PATCH] regmap: Ensure range selector registers are updated after cache sync

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Message-ID: <006e6dc4-1b5d-f46c-b03f-c60576dcf620@marcan.st>
Date:   Fri, 27 Oct 2023 08:55:54 +0900
From:   Hector Martin <marcan@...can.st>
To:     Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org
Subject: Re: [PATCH] regmap: Ensure range selector registers are updated after
 cache sync

On 27/10/2023 01.22, Mark Brown wrote:
> On Thu, Oct 26, 2023 at 04:49:19PM +0100, Mark Brown wrote:
>> When we sync the register cache we do so with the cache bypassed in order
>> to avoid overhead from writing the synced values back into the cache. If
>> the regmap has ranges and the selector register for those ranges is in a
>> register which is cached this has the unfortunate side effect of meaning
>> that the physical and cached copies of the selector register can be out of
>> sync after a cache sync. The cache will have whatever the selector was when
>> the sync started and the hardware will have the selector for the register
>> that was synced last.
> 
> Given the nearness to the release I've dropped this into my CI and am
> intending to just apply it as soon as that's done in the hopes that it
> hits tomorrow's -next and gets a bit more coverage, it would be great if
> you could confirm if this fixes the systems where you saw the original
> issue.

Can confirm, this fixes the sleep borking issue on my end after
reverting my workaround.

Tested-by: Hector Martin <marcan@...can.st>

- Hector