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Message-ID: <ZrzSxdxt64UkgVS3@p14s>
Date: Wed, 14 Aug 2024 09:52:37 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Beleswar Padhi <b-padhi@...com>
Cc: andersson@...nel.org, afd@...com, hnagalla@...com, u-kumar1@...com,
	s-anna@...com, linux-remoteproc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] remoteproc: k3-r5: Acquire mailbox handle during
 probe routine

Hi Beleswar,

On Thu, Aug 08, 2024 at 01:11:26PM +0530, Beleswar Padhi wrote:
> Acquire the mailbox handle during device probe and do not release handle
> in stop/detach routine or error paths. This removes the redundant
> requests for mbox handle later during rproc start/attach. This also
> allows to defer remoteproc driver's probe if mailbox is not probed yet.
> 
> Signed-off-by: Beleswar Padhi <b-padhi@...com>
> ---
>  drivers/remoteproc/ti_k3_r5_remoteproc.c | 78 +++++++++---------------
>  1 file changed, 30 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> index 57067308b3c0..8a63a9360c0f 100644
> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> @@ -194,6 +194,10 @@ static void k3_r5_rproc_mbox_callback(struct mbox_client *client, void *data)
>  	const char *name = kproc->rproc->name;
>  	u32 msg = omap_mbox_message(data);
>  
> +	/* Do not forward message from a detached core */
> +	if (kproc->rproc->state == RPROC_DETACHED)
> +		return;
> +
>  	dev_dbg(dev, "mbox msg: 0x%x\n", msg);
>  
>  	switch (msg) {
> @@ -229,6 +233,10 @@ static void k3_r5_rproc_kick(struct rproc *rproc, int vqid)
>  	mbox_msg_t msg = (mbox_msg_t)vqid;
>  	int ret;
>  
> +	/* Do not forward message to a detached core */
> +	if (kproc->rproc->state == RPROC_DETACHED)
> +		return;
> +
>  	/* send the index of the triggered virtqueue in the mailbox payload */
>  	ret = mbox_send_message(kproc->mbox, (void *)msg);
>  	if (ret < 0)
> @@ -399,12 +407,9 @@ static int k3_r5_rproc_request_mbox(struct rproc *rproc)
>  	client->knows_txdone = false;
>  
>  	kproc->mbox = mbox_request_channel(client, 0);
> -	if (IS_ERR(kproc->mbox)) {
> -		ret = -EBUSY;
> -		dev_err(dev, "mbox_request_channel failed: %ld\n",
> -			PTR_ERR(kproc->mbox));
> -		return ret;
> -	}
> +	if (IS_ERR(kproc->mbox))
> +		return dev_err_probe(dev, PTR_ERR(kproc->mbox),
> +				     "mbox_request_channel failed\n");
>  
>  	/*
>  	 * Ping the remote processor, this is only for sanity-sake for now;
> @@ -552,10 +557,6 @@ static int k3_r5_rproc_start(struct rproc *rproc)
>  	u32 boot_addr;
>  	int ret;
>  
> -	ret = k3_r5_rproc_request_mbox(rproc);
> -	if (ret)
> -		return ret;
> -
>  	boot_addr = rproc->bootaddr;
>  	/* TODO: add boot_addr sanity checking */
>  	dev_dbg(dev, "booting R5F core using boot addr = 0x%x\n", boot_addr);
> @@ -564,7 +565,7 @@ static int k3_r5_rproc_start(struct rproc *rproc)
>  	core = kproc->core;
>  	ret = ti_sci_proc_set_config(core->tsp, boot_addr, 0, 0);
>  	if (ret)
> -		goto put_mbox;
> +		return ret;
>  
>  	/* unhalt/run all applicable cores */
>  	if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
> @@ -580,13 +581,12 @@ static int k3_r5_rproc_start(struct rproc *rproc)
>  		if (core != core0 && core0->rproc->state == RPROC_OFFLINE) {
>  			dev_err(dev, "%s: can not start core 1 before core 0\n",
>  				__func__);
> -			ret = -EPERM;
> -			goto put_mbox;
> +			return -EPERM;
>  		}
>  
>  		ret = k3_r5_core_run(core);
>  		if (ret)
> -			goto put_mbox;
> +			return ret;
>  	}
>  
>  	return 0;
> @@ -596,8 +596,6 @@ static int k3_r5_rproc_start(struct rproc *rproc)
>  		if (k3_r5_core_halt(core))
>  			dev_warn(core->dev, "core halt back failed\n");
>  	}
> -put_mbox:
> -	mbox_free_channel(kproc->mbox);
>  	return ret;
>  }
>  
> @@ -658,8 +656,6 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>  			goto out;
>  	}
>  
> -	mbox_free_channel(kproc->mbox);
> -
>  	return 0;
>  
>  unroll_core_halt:
> @@ -674,42 +670,22 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>  /*
>   * Attach to a running R5F remote processor (IPC-only mode)
>   *
> - * The R5F attach callback only needs to request the mailbox, the remote
> - * processor is already booted, so there is no need to issue any TI-SCI
> - * commands to boot the R5F cores in IPC-only mode. This callback is invoked
> - * only in IPC-only mode.
> + * The R5F attach callback is a NOP. The remote processor is already booted, and
> + * all required resources have been acquired during probe routine, so there is
> + * no need to issue any TI-SCI commands to boot the R5F cores in IPC-only mode.
> + * This callback is invoked only in IPC-only mode and exists because
> + * rproc_validate() checks for its existence.

Excellent documentation.

>   */
> -static int k3_r5_rproc_attach(struct rproc *rproc)
> -{
> -	struct k3_r5_rproc *kproc = rproc->priv;
> -	struct device *dev = kproc->dev;
> -	int ret;
> -
> -	ret = k3_r5_rproc_request_mbox(rproc);
> -	if (ret)
> -		return ret;
> -
> -	dev_info(dev, "R5F core initialized in IPC-only mode\n");
> -	return 0;
> -}
> +static int k3_r5_rproc_attach(struct rproc *rproc) { return 0; }
>  
>  /*
>   * Detach from a running R5F remote processor (IPC-only mode)
>   *
> - * The R5F detach callback performs the opposite operation to attach callback
> - * and only needs to release the mailbox, the R5F cores are not stopped and
> - * will be left in booted state in IPC-only mode. This callback is invoked
> - * only in IPC-only mode.
> + * The R5F detach callback is a NOP. The R5F cores are not stopped and will be
> + * left in booted state in IPC-only mode. This callback is invoked only in
> + * IPC-only mode and exists for sanity sake.

I would add the part about detach() being a NOP to attach() above...

>   */
> -static int k3_r5_rproc_detach(struct rproc *rproc)
> -{
> -	struct k3_r5_rproc *kproc = rproc->priv;
> -	struct device *dev = kproc->dev;
> -
> -	mbox_free_channel(kproc->mbox);
> -	dev_info(dev, "R5F core deinitialized in IPC-only mode\n");
> -	return 0;
> -}
> +static int k3_r5_rproc_detach(struct rproc *rproc) { return 0; }

... and just remove this.

Otherwise this patch looks good.

>  
>  /*
>   * This function implements the .get_loaded_rsc_table() callback and is used
> @@ -1278,6 +1254,10 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
>  		kproc->rproc = rproc;
>  		core->rproc = rproc;
>  
> +		ret = k3_r5_rproc_request_mbox(rproc);
> +		if (ret)
> +			return ret;
> +
>  		ret = k3_r5_rproc_configure_mode(kproc);
>  		if (ret < 0)
>  			goto out;
> @@ -1392,6 +1372,8 @@ static void k3_r5_cluster_rproc_exit(void *data)
>  			}
>  		}
>  
> +		mbox_free_channel(kproc->mbox);
> +
>  		rproc_del(rproc);
>  
>  		k3_r5_reserved_mem_exit(kproc);
> -- 
> 2.34.1
> 

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