linux-kernel - Re: [PATCH] remoteproc: qcom_q6v5_pas: Do not fail if regulators are not found

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Message-ID: <YuZAvX13W9Qip7Ja@hovoldconsulting.com>
Date:   Sun, 31 Jul 2022 10:43:41 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     bjorn.andersson@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Abel Vesa <abel.vesa@...aro.org>,
        Steev Klimaszewski <steev@...i.org>
Subject: Re: [PATCH] remoteproc: qcom_q6v5_pas: Do not fail if regulators are
 not found

On Sat, Jul 30, 2022 at 11:58:34AM +0530, Manivannan Sadhasivam wrote:
> devm_regulator_get_optional() API will return -ENODEV if the regulator was
> not found. For the optional supplies CX, PX we should not fail in that case
> but rather continue. So let's catch that error and continue silently if
> those regulators are not found.
> 
> The commit 3f52d118f992 ("remoteproc: qcom_q6v5_pas: Deal silently with
> optional px and cx regulators") was supposed to do the same but it missed
> the fact that devm_regulator_get_optional() API returns -ENODEV when the
> regulator was not found.
> 
> Cc: Abel Vesa <abel.vesa@...aro.org>
> Fixes: 3f52d118f992 ("remoteproc: qcom_q6v5_pas: Deal silently with optional px and cx regulators")
> Reported-by: Steev Klimaszewski <steev@...i.org>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/remoteproc/qcom_q6v5_pas.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
> index 98f133f9bb60..5bf69ef53819 100644
> --- a/drivers/remoteproc/qcom_q6v5_pas.c
> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
> @@ -362,12 +362,24 @@ static int adsp_init_clock(struct qcom_adsp *adsp)
>  static int adsp_init_regulator(struct qcom_adsp *adsp)
>  {
>  	adsp->cx_supply = devm_regulator_get_optional(adsp->dev, "cx");
> -	if (IS_ERR(adsp->cx_supply))
> -		return PTR_ERR(adsp->cx_supply);
> +	if (IS_ERR(adsp->cx_supply)) {
> +		/* Do not fail if the regulator is not found */

I agree with Abel that these comments shouldn't be necessary.

> +		if (PTR_ERR(adsp->cx_supply) == -ENODEV)
> +			adsp->cx_supply = NULL;
> +		else
> +			return PTR_ERR(adsp->cx_supply);
> +	}
>  
> -	regulator_set_load(adsp->cx_supply, 100000);
> +	if (adsp->cx_supply)
> +		regulator_set_load(adsp->cx_supply, 100000);
>  
>  	adsp->px_supply = devm_regulator_get_optional(adsp->dev, "px");
> +	if (IS_ERR(adsp->px_supply)) {
> +		/* Do not fail if the regulator is not found */
> +		if (PTR_ERR(adsp->px_supply) == -ENODEV)
> +			adsp->px_supply = NULL;

Please return the error here as for cx.

> +	}
> +
>  	return PTR_ERR_OR_ZERO(adsp->px_supply);

And drop this abomination which just obfuscates code and return 0
explicitly in the success path.

With that fixed:

Reviewed-by: Johan Hovold <johan+linaro@...nel.org>

Johan