Re: [PATCH v4 3/3] remoteproc: k3-dsp: Acquire mailbox handle during probe routine

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Thu, Aug 08, 2024 at 01:11:27PM +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@ti.com>
> Acked-by: Andrew Davis <afd@ti.com>
> ---
>  drivers/remoteproc/ti_k3_dsp_remoteproc.c | 80 +++++++++--------------
>  1 file changed, 30 insertions(+), 50 deletions(-)
> 
> diff --git a/drivers/remoteproc/ti_k3_dsp_remoteproc.c b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> index a22d41689a7d..9009367e2891 100644
> --- a/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> +++ b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> @@ -115,6 +115,10 @@ static void k3_dsp_rproc_mbox_callback(struct mbox_client *client, void *data)
>  	const char *name = kproc->rproc->name;
>  	u32 msg = omap_mbox_message(data);
>  
> +	/* Do not forward messages from a detached core */
> +	if (kproc->rproc->state == RPROC_DETACHED)
> +		return;
> +
>  	dev_dbg(dev, "mbox msg: 0x%x\n", msg);
>  
>  	switch (msg) {
> @@ -155,6 +159,10 @@ static void k3_dsp_rproc_kick(struct rproc *rproc, int vqid)
>  	mbox_msg_t msg = (mbox_msg_t)vqid;
>  	int ret;
>  
> +	/* Do not forward messages 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)
> @@ -230,12 +238,9 @@ static int k3_dsp_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;
> @@ -315,32 +320,23 @@ static int k3_dsp_rproc_start(struct rproc *rproc)
>  	u32 boot_addr;
>  	int ret;
>  
> -	ret = k3_dsp_rproc_request_mbox(rproc);
> -	if (ret)
> -		return ret;
> -
>  	boot_addr = rproc->bootaddr;
>  	if (boot_addr & (kproc->data->boot_align_addr - 1)) {
>  		dev_err(dev, "invalid boot address 0x%x, must be aligned on a 0x%x boundary\n",
>  			boot_addr, kproc->data->boot_align_addr);
> -		ret = -EINVAL;
> -		goto put_mbox;
> +		return -EINVAL;
>  	}
>  
>  	dev_dbg(dev, "booting DSP core using boot addr = 0x%x\n", boot_addr);
>  	ret = ti_sci_proc_set_config(kproc->tsp, boot_addr, 0, 0);
>  	if (ret)
> -		goto put_mbox;
> +		return ret;
>  
>  	ret = k3_dsp_rproc_release(kproc);
>  	if (ret)
> -		goto put_mbox;
> +		return ret;
>  
>  	return 0;
> -
> -put_mbox:
> -	mbox_free_channel(kproc->mbox);
> -	return ret;
>  }
>  
>  /*
> @@ -353,8 +349,6 @@ static int k3_dsp_rproc_stop(struct rproc *rproc)
>  {
>  	struct k3_dsp_rproc *kproc = rproc->priv;
>  
> -	mbox_free_channel(kproc->mbox);
> -
>  	k3_dsp_rproc_reset(kproc);
>  
>  	return 0;
> @@ -363,42 +357,22 @@ static int k3_dsp_rproc_stop(struct rproc *rproc)
>  /*
>   * Attach to a running DSP remote processor (IPC-only mode)
>   *
> - * This rproc 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 DSP core. This callback is invoked only in IPC-only
> - * mode.
> + * This rproc 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 DSP core. This callback
> + * is invoked only in IPC-only mode and exists because rproc_validate() checks
> + * for its existence.
>   */
> -static int k3_dsp_rproc_attach(struct rproc *rproc)
> -{
> -	struct k3_dsp_rproc *kproc = rproc->priv;
> -	struct device *dev = kproc->dev;
> -	int ret;
> -
> -	ret = k3_dsp_rproc_request_mbox(rproc);
> -	if (ret)
> -		return ret;
> -
> -	dev_info(dev, "DSP initialized in IPC-only mode\n");
> -	return 0;
> -}
> +static int k3_dsp_rproc_attach(struct rproc *rproc) { return 0; }
>  
>  /*
>   * Detach from a running DSP remote processor (IPC-only mode)
>   *
> - * This rproc detach callback performs the opposite operation to attach callback
> - * and only needs to release the mailbox, the DSP core is not stopped and will
> - * be left to continue to run its booted firmware. This callback is invoked only
> - * in IPC-only mode.
> + * This rproc detach callback is a NOP. The DSP core is not stopped and will be
> + * left to continue to run its booted firmware. This callback is invoked only in
> + * IPC-only mode and exists for sanity sake.
>   */
> -static int k3_dsp_rproc_detach(struct rproc *rproc)
> -{
> -	struct k3_dsp_rproc *kproc = rproc->priv;
> -	struct device *dev = kproc->dev;
> -
> -	mbox_free_channel(kproc->mbox);
> -	dev_info(dev, "DSP deinitialized in IPC-only mode\n");
> -	return 0;
> -}
> +static int k3_dsp_rproc_detach(struct rproc *rproc) { return 0; }

Same comment as the previous patch.

Thanks,
Mathieu

>  
>  /*
>   * This function implements the .get_loaded_rsc_table() callback and is used
> @@ -697,6 +671,10 @@ static int k3_dsp_rproc_probe(struct platform_device *pdev)
>  	kproc->dev = dev;
>  	kproc->data = data;
>  
> +	ret = k3_dsp_rproc_request_mbox(rproc);
> +	if (ret)
> +		return ret;
> +
>  	kproc->ti_sci = devm_ti_sci_get_by_phandle(dev, "ti,sci");
>  	if (IS_ERR(kproc->ti_sci))
>  		return dev_err_probe(dev, PTR_ERR(kproc->ti_sci),
> @@ -789,6 +767,8 @@ static void k3_dsp_rproc_remove(struct platform_device *pdev)
>  		if (ret)
>  			dev_err(dev, "failed to detach proc (%pe)\n", ERR_PTR(ret));
>  	}
> +
> +	mbox_free_channel(kproc->mbox);
>  }
>  
>  static const struct k3_dsp_mem_data c66_mems[] = {
> -- 
> 2.34.1
>