linux-kernel - Re: [PATCH v2] mfd: stpmic1: Attempt system shutdown twice in case PMIC is confused

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Message-ID: <20260120171853.GH1354723@google.com>
Date: Tue, 20 Jan 2026 17:18:53 +0000
From: Lee Jones <lee@...nel.org>
To: Marek Vasut <marex@...ladev.com>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Pascal PAILLET-LME <p.paillet@...com>,
	Paul Cercueil <paul@...pouillou.net>,
	Sean Nyekjaer <sean@...nix.com>, kernel@...electronics.com
Subject: Re: [PATCH v2] mfd: stpmic1: Attempt system shutdown twice in case
 PMIC is confused

On Thu, 15 Jan 2026, Marek Vasut wrote:

> Attempt to shut down again, in case the first attempt failed.
> The STPMIC1 might get confused and the first regmap_update_bits()
> returns with -ETIMEDOUT / -110 . If that or similar transient
> failure occurs, try to shut down again. If the second attempt
> fails, there is some bigger problem, report it to user.
> 
> Cc: stable@...r.kernel.org
> Fixes: 6e9df38f359a ("mfd: stpmic1: Add PMIC poweroff via sys-off handler")
> Signed-off-by: Marek Vasut <marex@...ladev.com>
> ---
> Cc: Lee Jones <lee@...nel.org>
> Cc: Pascal PAILLET-LME <p.paillet@...com>
> Cc: Paul Cercueil <paul@...pouillou.net>
> Cc: Sean Nyekjaer <sean@...nix.com>
> Cc: kernel@...electronics.com
> ---
> V2: - Use a retry loop
>     - Cc stable
> ---
>  drivers/mfd/stpmic1.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mfd/stpmic1.c b/drivers/mfd/stpmic1.c
> index 081827bc05961..9caf2b8740829 100644
> --- a/drivers/mfd/stpmic1.c
> +++ b/drivers/mfd/stpmic1.c
> @@ -121,9 +121,24 @@ static const struct regmap_irq_chip stpmic1_regmap_irq_chip = {
>  static int stpmic1_power_off(struct sys_off_data *data)
>  {
>  	struct stpmic1 *ddata = data->cb_data;
> -
> -	regmap_update_bits(ddata->regmap, MAIN_CR,
> -			   SOFTWARE_SWITCH_OFF, SOFTWARE_SWITCH_OFF);
> +	int i, ret;
> +
> +	for (i = 0; i < 2; i++) {

  for (int retries = 0; retries < MAX_RETIRES; retries++)

> +		ret = regmap_update_bits(ddata->regmap, MAIN_CR, SOFTWARE_SWITCH_OFF,
> +					 SOFTWARE_SWITCH_OFF);
> +		if (!ret)
> +			return NOTIFY_DONE;
> +
> +		/*
> +		 * Attempt to shut down again, in case the first attempt failed.
> +		 * The STPMIC1 might get confused and the first regmap_update_bits()
> +		 * returns with -ETIMEDOUT / -110 . If that or similar transient
> +		 * failure occurs, try to shut down again. If the second attempt
> +		 * fails, there is some bigger problem, report it to user.
> +		 */
> +		if (i)
> +			dev_err(ddata->dev, "Failed to access PMIC I2C bus (%d)\n", ret);

Users aren't going to care if this works on the first or second attempt.

I would only issue the error once we've given up.

No return error in the fail case?

  define NOTIFY_DONE             0x0000          /* Don't care */

Harsh!

> +	}
>  
>  	return NOTIFY_DONE;
>  }
> -- 
> 2.51.0
> 

-- 
Lee Jones [李琼斯]