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Date:   Tue, 11 Aug 2020 16:36:06 -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 10/10] remoteproc: imx_rproc: support coproc booting
 before Linux
Message-ID: <20200811223606.GD3370567@xps15>
References: <20200724080813.24884-1-peng.fan@nxp.com>
 <20200724080813.24884-11-peng.fan@nxp.com>
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On Fri, Jul 24, 2020 at 04:08:13PM +0800, Peng Fan wrote:
> Detect Coproc booted or not and Parse resource table
> Set remoteproc state to RPROC_DETACHED when M4 is booted early
> Add attach hook
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
>  drivers/remoteproc/imx_rproc.c | 75 ++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 73 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index a8ce97c04e1e..0863b3162777 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -91,6 +91,7 @@ struct imx_rproc {
>  	const struct imx_rproc_dcfg	*dcfg;
>  	struct imx_rproc_mem		mem[IMX7D_RPROC_MEM_MAX];
>  	struct clk			*clk;
> +	bool				early_boot;
>  	void				*rsc_va;
>  	struct mbox_client		cl;
>  	struct mbox_chan		*tx_ch;
> @@ -235,6 +236,8 @@ static int imx_rproc_stop(struct rproc *rproc)
>  				 dcfg->src_mask, dcfg->src_stop);
>  	if (ret)
>  		dev_err(dev, "Failed to stop M4!\n");
> +	else
> +		priv->early_boot = false;
>  
>  	return ret;
>  }
> @@ -390,6 +393,32 @@ static int imx_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
>  	return 0;
>  }
>  
> +static int imx_rproc_get_loaded_rsc_table(struct device *dev,
> +					  struct rproc *rproc)
> +{
> +	struct imx_rproc *priv = rproc->priv;
> +	struct device_node *np = dev->of_node;
> +	u32 da;
> +	int ret;
> +
> +	ret = of_property_read_u32(np, "rsc-da", &da);

As Rob pointed out I don't think there is a need to invent a new bindings for
this.  It could simply be a memory region that is looked up with a name.

> +	if (!ret)
> +		priv->rsc_va = rproc_da_to_va(rproc, (u64)da, SZ_1K);
> +	else
> +		return 0;
> +
> +	if (!priv->rsc_va) {
> +		dev_err(priv->dev, "no map for rsc-da: %x\n", da);
> +		return PTR_ERR(priv->rsc_va);
> +	}
> +
> +	rproc->table_ptr = (struct resource_table *)priv->rsc_va;
> +	rproc->table_sz = SZ_1K;
> +	rproc->cached_table = NULL;
> +
> +	return 0;
> +}
> +
>  static int imx_rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw)
>  {
>  	struct device *dev = &rproc->dev;
> @@ -472,9 +501,15 @@ static void imx_rproc_kick(struct rproc *rproc, int vqid)
>  			__func__, vqid, err);
>  }
>  
> +static int imx_rproc_attach(struct rproc *rproc)
> +{
> +	return 0;
> +}
> +
>  static const struct rproc_ops imx_rproc_ops = {
>  	.start		= imx_rproc_start,
>  	.stop		= imx_rproc_stop,
> +	.attach		= imx_rproc_attach,
>  	.kick		= imx_rproc_kick,
>  	.da_to_va       = imx_rproc_da_to_va,
>  	.load		= imx_rproc_elf_load_segments,
> @@ -609,6 +644,36 @@ static int imx_rproc_xtr_mbox_init(struct rproc *rproc)
>  	return ret;
>  }
>  
> +static int imx_rproc_detect_mode(struct imx_rproc *priv)
> +{
> +	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
> +	struct device *dev = priv->dev;
> +	int ret;
> +	u32 val;
> +
> +	ret = regmap_read(priv->regmap, dcfg->src_reg, &val);

Patch 04 made it possible for priv->regmap to be NULL and as far as I can see
there is no further check on the value of ->regmap before we get to this
function.

> +	if (ret) {
> +		dev_err(dev, "Failed to read src\n");
> +		return ret;
> +	}
> +
> +	priv->early_boot = !(val & dcfg->src_stop);

Please add a comment that describe the condition.  As much as I try guessing
the relation between ->src_stop and an already booted co-processor I come out
short. 

> +
> +	if (priv->early_boot) {

I don't see a need for ->early_boot, please re-arrange the code in
imx_rproc_probe() to avoid needing yet an extra variable. 

> +		priv->rproc->state = RPROC_DETACHED;
> +
> +		ret = imx_rproc_parse_memory_regions(priv->rproc);
> +		if (ret)
> +			return ret;
> +
> +		ret = imx_rproc_get_loaded_rsc_table(dev, priv->rproc);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int imx_rproc_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -661,6 +726,10 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  		goto err_put_mbox;
>  	}
>  
> +	ret = imx_rproc_detect_mode(priv);
> +	if (ret)
> +		goto err_put_mbox;
> +
>  	priv->clk = devm_clk_get_optional(dev, NULL);
>  	if (IS_ERR(priv->clk)) {
>  		dev_err(dev, "Failed to get clock\n");
> @@ -689,7 +758,8 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  	return 0;
>  
>  err_put_clk:
> -	clk_disable_unprepare(priv->clk);
> +	if (!priv->early_boot)
> +		clk_disable_unprepare(priv->clk);
>  err_put_mbox:
>  	if (!IS_ERR(priv->tx_ch))
>  		mbox_free_channel(priv->tx_ch);
> @@ -706,7 +776,8 @@ static int imx_rproc_remove(struct platform_device *pdev)
>  	struct rproc *rproc = platform_get_drvdata(pdev);
>  	struct imx_rproc *priv = rproc->priv;
>  
> -	clk_disable_unprepare(priv->clk);
> +	if (!priv->early_boot)
> +		clk_disable_unprepare(priv->clk);
>  	rproc_del(rproc);
>  	rproc_free(rproc);
>  
> -- 
> 2.16.4
>