linux-kernel - Re: [PATCH] regulator: core: Clean up on enable failure

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Date:   Fri, 19 Aug 2022 13:03:31 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Andrew Halaney <ahalaney@...hat.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, bmasney@...hat.com
Subject: Re: [PATCH] regulator: core: Clean up on enable failure

Hi,

On Fri, Aug 19, 2022 at 12:44 PM Andrew Halaney <ahalaney@...hat.com> wrote:
>
> If regulator_enable() fails, enable_count is incremented still.
> A consumer, assuming no matching regulator_disable() is necessary on
> failure, will then get this error message upon regulator_put()
> since enable_count is non-zero:
>
>     [    1.277418] WARNING: CPU: 3 PID: 1 at drivers/regulator/core.c:2304 _regulator_put.part.0+0x168/0x170
>
> The consumer could try to fix this in their driver by cleaning up on
> error from regulator_enable() (i.e. call regulator_disable()), but that
> results in the following since regulator_enable() failed and didn't
> increment user_count:
>
>     [    1.258112] unbalanced disables for vreg_l17c
>     [    1.262606] WARNING: CPU: 4 PID: 1 at drivers/regulator/core.c:2899 _regulator_disable+0xd4/0x190
>
> Fix this by decrementing enable_count upon failure to enable.
>
> With this in place, just the reason for failure to enable is printed
> as expected and developers can focus on the root cause of their issue
> instead of thinking their usage of the regulator consumer api is
> incorrect. For example, in my case:
>
>     [    1.240426] vreg_l17c: invalid input voltage found
>
> Fixes: 5451781dadf8 ("regulator: core: Only count load for enabled consumers")
> Signed-off-by: Andrew Halaney <ahalaney@...hat.com>
> ---
>
> I'm new to using the regulator framework, but I _believe_ this is a
> cosmetic bug that's fixed by this patch. I went down a bit of a rabbit
> hole because of the original WARN() message, so I'm trying to prevent
> others from doing the same :)
>
> Please let me know what you think, I tested on the misconfigured system
> and on a working system and things seemed to work as expected.
>
> Thanks,
> Andrew
>
>  drivers/regulator/core.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

This looks right to me. Thanks!

Reviewed-by: Douglas Anderson <dianders@...omium.org>