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Date:   Tue, 11 Aug 2020 16:40:29 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Peng Fan <peng.fan@nxp.com>
Cc:     bjorn.andersson@linaro.org, o.rempel@pengutronix.de,
        robh+dt@kernel.org, linux-remoteproc@vger.kernel.org,
        linux-kernel@vger.kernel.org, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
        linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org,
        devicetree@vger.kernel.org
Subject: Re: [PATCH 04/10] remoteproc: imx_rproc: make syscon optional
Message-ID: <20200811224029.GE3370567@xps15>
References: <20200724080813.24884-1-peng.fan@nxp.com>
 <20200724080813.24884-5-peng.fan@nxp.com>
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On Fri, Jul 24, 2020 at 04:08:07PM +0800, Peng Fan wrote:
> Make syscon optional, since i.MX8QM/QXP/7ULP not have SRC to control M4.
> But currently i.MX8QM/QXP/7ULP not added, so still check regmap
> when start/stop to avoid unhappy things.
> 
> Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
>  drivers/remoteproc/imx_rproc.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index 82594a800a1b..4fad5c0b1c05 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -162,6 +162,9 @@ static int imx_rproc_start(struct rproc *rproc)
>  	struct device *dev = priv->dev;
>  	int ret;
>  
> +	if (!priv->regmap)
> +		return -EOPNOTSUPP;

Proceeding this way is hard to maintain.  I would perfer to add specific
operations based on the scenario or coprocessor we are working with.

> +
>  	ret = regmap_update_bits(priv->regmap, dcfg->src_reg,
>  				 dcfg->src_mask, dcfg->src_start);
>  	if (ret)
> @@ -177,6 +180,9 @@ static int imx_rproc_stop(struct rproc *rproc)
>  	struct device *dev = priv->dev;
>  	int ret;
>  
> +	if (!priv->regmap)
> +		return -EOPNOTSUPP;
> +
>  	ret = regmap_update_bits(priv->regmap, dcfg->src_reg,
>  				 dcfg->src_mask, dcfg->src_stop);
>  	if (ret)
> @@ -325,9 +331,10 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  	regmap = syscon_regmap_lookup_by_phandle(np, "syscon");
>  	if (IS_ERR(regmap)) {
>  		dev_err(dev, "failed to find syscon\n");
> -		return PTR_ERR(regmap);
> +		regmap = NULL;
> +	} else {
> +		regmap_attach_dev(dev, regmap, &config);

Here you are altering how all the existing implemenation are currently working.
Add a new field to imx_rproc_dcfg and based on that, determine if a regmap is
mandatory or not.

>  	}
> -	regmap_attach_dev(dev, regmap, &config);
>  
>  	/* set some other name then imx */
>  	rproc = rproc_alloc(dev, "imx-rproc", &imx_rproc_ops,
> -- 
> 2.16.4
>