Date:   Fri, 4 Dec 2020 18:44:25 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     ohad@...ery.com, mathieu.poirier@...aro.org,
        o.rempel@...gutronix.de, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Peng Fan <peng.fan@....com>, Richard Zhu <hongxing.zhu@....com>
Subject: Re: [PATCH V3 7/7] remoteproc: imx_proc: enable virtio/mailbox

On Fri 04 Dec 01:40 CST 2020, Peng Fan (OSS) wrote:

> From: Peng Fan <peng.fan@....com>
> 
> Use virtio/mailbox to build connection between Remote Proccessors
> and Linux. Add work queue to handle incoming messages.
> 
> Reviewed-by: Richard Zhu <hongxing.zhu@....com>
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/remoteproc/imx_rproc.c | 133 ++++++++++++++++++++++++++++++++-
>  1 file changed, 130 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index afa650610996..584584a00921 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -8,6 +8,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
> +#include <linux/mailbox_client.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/module.h>
>  #include <linux/of_address.h>
> @@ -16,6 +17,9 @@
>  #include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  #include <linux/remoteproc.h>
> +#include <linux/workqueue.h>
> +
> +#include "remoteproc_internal.h"
>  
>  #define IMX7D_SRC_SCR			0x0C
>  #define IMX7D_ENABLE_M4			BIT(3)
> @@ -88,6 +92,11 @@ struct imx_rproc {
>  	const struct imx_rproc_dcfg	*dcfg;
>  	struct imx_rproc_mem		mem[IMX7D_RPROC_MEM_MAX];
>  	struct clk			*clk;
> +	struct mbox_client		cl;
> +	struct mbox_chan		*tx_ch;
> +	struct mbox_chan		*rx_ch;
> +	struct work_struct		rproc_work;
> +	struct workqueue_struct		*workqueue;
>  };
>  
>  static const struct imx_rproc_att imx_rproc_att_imx8mq[] = {
> @@ -369,9 +378,33 @@ static int imx_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
>  	return 0;
>  }
>  
> +static void imx_rproc_kick(struct rproc *rproc, int vqid)
> +{
> +	struct imx_rproc *priv = rproc->priv;
> +	int err;
> +	__u32 mmsg;
> +
> +	if (!priv->tx_ch) {
> +		dev_err(priv->dev, "No initialized mbox tx channel\n");
> +		return;
> +	}
> +
> +	/*
> +	 * Send the index of the triggered virtqueue as the mu payload.
> +	 * Let remote processor know which virtqueue is used.
> +	 */
> +	mmsg = vqid << 16;
> +
> +	err = mbox_send_message(priv->tx_ch, (void *)&mmsg);
> +	if (err < 0)
> +		dev_err(priv->dev, "%s: failed (%d, err:%d)\n",
> +			__func__, vqid, err);
> +}
> +
>  static const struct rproc_ops imx_rproc_ops = {
>  	.start		= imx_rproc_start,
>  	.stop		= imx_rproc_stop,
> +	.kick		= imx_rproc_kick,
>  	.da_to_va       = imx_rproc_da_to_va,
>  	.load		= rproc_elf_load_segments,
>  	.parse_fw	= imx_rproc_parse_fw,
> @@ -454,6 +487,77 @@ static void imx_rproc_memset(struct rproc *rproc, void *s, int c, size_t count)
>  	memset_io((void * __iomem)s, c, count);
>  }
>  
> +static void imx_rproc_vq_work(struct work_struct *work)
> +{
> +	struct imx_rproc *priv = container_of(work, struct imx_rproc,
> +					      rproc_work);
> +
> +	rproc_vq_interrupt(priv->rproc, 0);
> +	rproc_vq_interrupt(priv->rproc, 1);
> +}
> +
> +static void imx_rproc_rx_callback(struct mbox_client *cl, void *msg)
> +{
> +	struct rproc *rproc = dev_get_drvdata(cl->dev);
> +	struct imx_rproc *priv = rproc->priv;
> +
> +	queue_work(priv->workqueue, &priv->rproc_work);
> +}
> +
> +static int imx_rproc_xtr_mbox_init(struct rproc *rproc)
> +{
> +	struct imx_rproc *priv = rproc->priv;
> +	struct device *dev = priv->dev;
> +	struct mbox_client *cl;
> +	int ret = 0;
> +
> +	if (!of_get_property(dev->of_node, "mbox-names", NULL))
> +		return 0;
> +
> +	cl = &priv->cl;
> +	cl->dev = dev;
> +	cl->tx_block = true;
> +	cl->tx_tout = 100;
> +	cl->knows_txdone = false;
> +	cl->rx_callback = imx_rproc_rx_callback;
> +
> +	priv->tx_ch = mbox_request_channel_byname(cl, "tx");
> +	if (IS_ERR(priv->tx_ch)) {
> +		if (PTR_ERR(priv->tx_ch) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +		ret = PTR_ERR(priv->tx_ch);
> +		dev_dbg(cl->dev, "failed to request mbox tx chan, ret %d\n",
> +			ret);

This is worse than a dev_dbg(), something is actually wrong.
Also there's no point in jumping to err_out here, because tx_ch is
IS_ERR() so we're going to skip the first part and rx_ch is not IS_ERR()
so you're going to call mbox_free_channel(NULL) and then return.

So just replace this entire block with:

		return dev_err_probe(dev, PTR_ERR(priv->ch_ch),
				     "failed to request tx mailbox channel: %d\n",
				     ret);
	

> +		goto err_out;
> +	}
> +
> +	priv->rx_ch = mbox_request_channel_byname(cl, "rx");
> +	if (IS_ERR(priv->rx_ch)) {
> +		ret = PTR_ERR(priv->rx_ch);
> +		dev_dbg(cl->dev, "failed to request mbox rx chan, ret %d\n",
> +			ret);
> +		goto err_out;

		mbox_free_channel(priv->tx_ch);
		return dev_err_probe(dev, PTR_ERR(priv->ch_ch),
				     "failed to request rx mailbox channel: %d\n",
				     ret);

> +	}
> +
> +	return ret;

ret is 0 here.

> +
> +err_out:
> +	if (!IS_ERR(priv->tx_ch))
> +		mbox_free_channel(priv->tx_ch);
> +	if (!IS_ERR(priv->rx_ch))
> +		mbox_free_channel(priv->rx_ch);
> +
> +	return ret;
> +}
> +
> +static void imx_rproc_free_mbox(struct rproc *rproc)
> +{
> +	struct imx_rproc *priv = rproc->priv;
> +
> +	mbox_free_channel(priv->tx_ch);
> +	mbox_free_channel(priv->rx_ch);
> +}
> +
>  static int imx_rproc_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -496,18 +600,31 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  	priv->dev = dev;
>  
>  	dev_set_drvdata(dev, rproc);
> +	priv->workqueue = create_workqueue(dev_name(dev));
> +	if (!priv->workqueue) {
> +		dev_err(dev, "cannot create workqueue\n");
> +		ret = -ENOMEM;
> +		goto err_put_rproc;
> +	}
> +
> +	ret = imx_rproc_xtr_mbox_init(rproc);
> +	if (ret) {
> +		if (ret == -EPROBE_DEFER)
> +			goto err_put_wkq;
> +		/* mbox is optional, so not fail here */

imx_rproc_xtr_mbox_init() returns 0 if no mbox was specified, that means
that in all cases that we reach here mailboxes where specified but an
error occurred. You should not ignore this.

> +	}
>  
>  	ret = imx_rproc_addr_init(priv, pdev);
>  	if (ret) {
>  		dev_err(dev, "failed on imx_rproc_addr_init\n");
> -		goto err_put_rproc;
> +		goto err_put_mbox;
>  	}
>  
>  	priv->clk = devm_clk_get(dev, NULL);
>  	if (IS_ERR(priv->clk)) {
>  		dev_err(dev, "Failed to get clock\n");
>  		ret = PTR_ERR(priv->clk);
> -		goto err_put_rproc;
> +		goto err_put_mbox;
>  	}
>  
>  	/*
> @@ -517,9 +634,11 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  	ret = clk_prepare_enable(priv->clk);
>  	if (ret) {
>  		dev_err(&rproc->dev, "Failed to enable clock\n");
> -		goto err_put_rproc;
> +		goto err_put_mbox;
>  	}
>  
> +	INIT_WORK(&(priv->rproc_work), imx_rproc_vq_work);
> +
>  	ret = rproc_add(rproc);
>  	if (ret) {
>  		dev_err(dev, "rproc_add failed\n");
> @@ -530,6 +649,13 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  
>  err_put_clk:
>  	clk_disable_unprepare(priv->clk);
> +err_put_mbox:
> +	if (!IS_ERR(priv->tx_ch))

With above changes you won't get here with IS_ERR(tx_ch) ||
IS_ERR(rx_ch), so you can safely remove the conditionals and just call
mbox_free_channel().

Regards,
Bjorn

> +		mbox_free_channel(priv->tx_ch);
> +	if (!IS_ERR(priv->rx_ch))
> +		mbox_free_channel(priv->rx_ch);
> +err_put_wkq:
> +	destroy_workqueue(priv->workqueue);
>  err_put_rproc:
>  	rproc_free(rproc);
>  
> @@ -542,6 +668,7 @@ static int imx_rproc_remove(struct platform_device *pdev)
>  	struct imx_rproc *priv = rproc->priv;
>  
>  	clk_disable_unprepare(priv->clk);
> +	imx_rproc_free_mbox(rproc);
>  	rproc_del(rproc);
>  	rproc_free(rproc);
>  
> -- 
> 2.28.0
> 

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