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Message-ID: <e7b98867-3493-4c76-863a-a04795333620@ti.com>
Date: Tue, 4 Jun 2024 12:10:18 -0500
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Subject: Re: [PATCH v2 2/3] remoteproc: k3-r5: Acquire mailbox handle during
 probe
To: Beleswar Padhi <b-padhi@ti.com>, <andersson@kernel.org>,
        <mathieu.poirier@linaro.org>
CC: <hnagalla@ti.com>, <u-kumar1@ti.com>, <linux-remoteproc@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <20240604051722.3608750-1-b-padhi@ti.com>
 <20240604051722.3608750-3-b-padhi@ti.com>
Content-Language: en-US
From: Andrew Davis <afd@ti.com>
In-Reply-To: <20240604051722.3608750-3-b-padhi@ti.com>
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On 6/4/24 12:17 AM, 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@ti.com>
> ---
>   drivers/remoteproc/ti_k3_r5_remoteproc.c | 74 +++++++++---------------
>   1 file changed, 26 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> index 26362a509ae3c..7e02e3472ce25 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 to a detached core */

s/to/from

This is the receive side from the core.

> +	if (kproc->rproc->state == RPROC_DETACHED)
> +		return;
> +

Do we need a similar check when sending messages to the core in
k3_r5_rproc_kick()? No one should be sending anything as they
all should have detached at this point, but something to double
check on.

>   	dev_dbg(dev, "mbox msg: 0x%x\n", msg);
>   
>   	switch (msg) {
> @@ -399,12 +403,9 @@ 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");

This is good cleanup, but maybe something for its own patch.

>   
>   	/*
>   	 * Ping the remote processor, this is only for sanity-sake for now;
> @@ -552,10 +553,6 @@ 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 +561,7 @@ 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 +577,12 @@ 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 +592,6 @@ 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 +652,6 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>   			goto out;
>   	}
>   
> -	mbox_free_channel(kproc->mbox);
> -
>   	return 0;
>   
>   unroll_core_halt:
> @@ -674,42 +666,22 @@ 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.
>    */
> -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; }

I wonder if rproc_validate() should be updated to allow not
having an attach/detach for cases like this. Then we could drop
this function completely.

Andrew

>   
>   /*
>    * 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.
>    */
> -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; }
>   
>   /*
>    * This function implements the .get_loaded_rsc_table() callback and is used
> @@ -1277,6 +1249,10 @@ 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 err_config;
> @@ -1393,6 +1369,8 @@ static void k3_r5_cluster_rproc_exit(void *data)
>   			}
>   		}
>   
> +		mbox_free_channel(kproc->mbox);
> +
>   		rproc_del(rproc);
>   
>   		k3_r5_reserved_mem_exit(kproc);