linux-kernel - Re: [PATCH 4/5] remoteproc: stm32: Allow hold boot management by the SCMI reset controller

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Message-ID: <20230405180143.GD3812912@p14s>
Date:   Wed, 5 Apr 2023 12:01:43 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc:     Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 4/5] remoteproc: stm32: Allow hold boot management by the
 SCMI reset controller

On Fri, Mar 31, 2023 at 05:46:50PM +0200, Arnaud Pouliquen wrote:
> The hold boot can be managed by the SCMI controller as a reset.
> If the "hold_boot" reset is defined in the device tree, use it.
> Else use the syscon controller directly to access to the register.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> ---
>  drivers/remoteproc/stm32_rproc.c | 34 ++++++++++++++++++++++++++------
>  1 file changed, 28 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
> index 4be651e734ee..6b0d8f30a5c7 100644
> --- a/drivers/remoteproc/stm32_rproc.c
> +++ b/drivers/remoteproc/stm32_rproc.c
> @@ -78,6 +78,7 @@ struct stm32_mbox {
>  
>  struct stm32_rproc {
>  	struct reset_control *rst;
> +	struct reset_control *hold_boot_rst;
>  	struct stm32_syscon hold_boot;
>  	struct stm32_syscon pdds;
>  	struct stm32_syscon m4_state;
> @@ -398,6 +399,14 @@ static int stm32_rproc_set_hold_boot(struct rproc *rproc, bool hold)
>  	struct stm32_syscon hold_boot = ddata->hold_boot;
>  	int val, err;
>  
> +	if (ddata->hold_boot_rst) {
> +		/* Use the SCMI reset controller */
> +		if (!hold)
> +			return reset_control_deassert(ddata->hold_boot_rst);
> +		else
> +			return reset_control_assert(ddata->hold_boot_rst);
> +	}
> +
>  	val = hold ? HOLD_BOOT : RELEASE_BOOT;
>  
>  	err = regmap_update_bits(hold_boot.map, hold_boot.reg,
> @@ -693,16 +702,29 @@ static int stm32_rproc_parse_dt(struct platform_device *pdev,
>  		dev_info(dev, "wdg irq registered\n");
>  	}
>  
> -	ddata->rst = devm_reset_control_get_by_index(dev, 0);
> +	ddata->rst = devm_reset_control_get(dev, "mcu_rst");

Peng is correct - newer kernels won't be able to boot with older DT.

>  	if (IS_ERR(ddata->rst))
>  		return dev_err_probe(dev, PTR_ERR(ddata->rst),
>  				     "failed to get mcu_reset\n");
>  
> -	err = stm32_rproc_get_syscon(np, "st,syscfg-holdboot",
> -				     &ddata->hold_boot);
> -	if (err) {
> -		dev_err(dev, "failed to get hold boot\n");
> -		return err;
> +	ddata->hold_boot_rst = devm_reset_control_get(dev, "hold_boot");
> +	if (IS_ERR(ddata->hold_boot_rst)) {
> +		if (PTR_ERR(ddata->hold_boot_rst) == -EPROBE_DEFER)
> +			return PTR_ERR(ddata->hold_boot_rst);
> +		ddata->hold_boot_rst = NULL;
> +	}
> +
> +	if (!ddata->hold_boot_rst) {

Why another if() statement?  The code below should be in the above if()...

This patchset is surprizingly confusing for its size.  I suggest paying
attention to the changelogs and adding comments in the code.

Thanks,
Mathieu

> +		/*
> +		 * If the hold boot is not managed by the SCMI reset controller,
> +		 * manage it through the syscon controller
> +		 */
> +		err = stm32_rproc_get_syscon(np, "st,syscfg-holdboot",
> +					     &ddata->hold_boot);
> +		if (err) {
> +			dev_err(dev, "failed to get hold boot\n");
> +			return err;
> +		}
>  	}
>  
>  	err = stm32_rproc_get_syscon(np, "st,syscfg-pdds", &ddata->pdds);
> -- 
> 2.25.1
>