linux-kernel - Re: [PATCH v2 1/2] remoteproc: k3-r5: Wait for core0 power-up before powering up core1

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Message-ID: <Zivf4Bhi8zqEQh7p@p14s>
Date: Fri, 26 Apr 2024 11:09:52 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Beleswar Padhi <b-padhi@...com>
Cc: andersson@...nel.org, s-anna@...com, linux-remoteproc@...r.kernel.org,
	linux-kernel@...r.kernel.org, u-kumar1@...com, nm@...com,
	devarsht@...com, hnagalla@...com
Subject: Re: [PATCH v2 1/2] remoteproc: k3-r5: Wait for core0 power-up before
 powering up core1

Good day,

On Wed, Apr 24, 2024 at 06:35:03PM +0530, Beleswar Padhi wrote:
> From: Apurva Nandan <a-nandan@...com>
> 
> PSC controller has a limitation that it can only power-up the second core
> when the first core is in ON state. Power-state for core0 should be equal
> to or higher than core1, else the kernel is seen hanging during rproc
> loading.
> 
> Make the powering up of cores sequential, by waiting for the current core
> to power-up before proceeding to the next core, with a timeout of 2sec.
> Add a wait queue event in k3_r5_cluster_rproc_init call, that will wait
> for the current core to be released from reset before proceeding with the
> next core.
> 
> Fixes: 6dedbd1d5443 ("remoteproc: k3-r5: Add a remoteproc driver for R5F subsystem")
> 
> Signed-off-by: Apurva Nandan <a-nandan@...com>

You need to add your own SoB as well.

> ---
>  drivers/remoteproc/ti_k3_r5_remoteproc.c | 28 ++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> index ad3415a3851b..5a9bd5d4a2ea 100644
> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> @@ -103,12 +103,14 @@ struct k3_r5_soc_data {
>   * @dev: cached device pointer
>   * @mode: Mode to configure the Cluster - Split or LockStep
>   * @cores: list of R5 cores within the cluster
> + * @core_transition: wait queue to sync core state changes
>   * @soc_data: SoC-specific feature data for a R5FSS
>   */
>  struct k3_r5_cluster {
>  	struct device *dev;
>  	enum cluster_mode mode;
>  	struct list_head cores;
> +	wait_queue_head_t core_transition;
>  	const struct k3_r5_soc_data *soc_data;
>  };
>  
> @@ -128,6 +130,7 @@ struct k3_r5_cluster {
>   * @atcm_enable: flag to control ATCM enablement
>   * @btcm_enable: flag to control BTCM enablement
>   * @loczrama: flag to dictate which TCM is at device address 0x0
> + * @released_from_reset: flag to signal when core is out of reset
>   */
>  struct k3_r5_core {
>  	struct list_head elem;
> @@ -144,6 +147,7 @@ struct k3_r5_core {
>  	u32 atcm_enable;
>  	u32 btcm_enable;
>  	u32 loczrama;
> +	bool released_from_reset;
>  };
>  
>  /**
> @@ -460,6 +464,8 @@ static int k3_r5_rproc_prepare(struct rproc *rproc)
>  			ret);
>  		return ret;
>  	}
> +	core->released_from_reset = true;
> +	wake_up_interruptible(&cluster->core_transition);
>  
>  	/*
>  	 * Newer IP revisions like on J7200 SoCs support h/w auto-initialization
> @@ -1140,6 +1146,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
>  		return ret;
>  	}
>  
> +	core->released_from_reset = c_state;

I understand why this is needed but it line could be very cryptic for people
trying to understand this driver.  Please add a comment to describe what is
happening here.

>  	ret = ti_sci_proc_get_status(core->tsp, &boot_vec, &cfg, &ctrl,
>  				     &stat);
>  	if (ret < 0) {
> @@ -1280,6 +1287,26 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
>  		    cluster->mode == CLUSTER_MODE_SINGLECPU ||
>  		    cluster->mode == CLUSTER_MODE_SINGLECORE)
>  			break;
> +
> +		/*
> +		 * R5 cores require to be powered on sequentially, core0
> +		 * should be in higher power state than core1 in a cluster
> +		 * So, wait for current core to power up before proceeding
> +		 * to next core and put timeout of 2sec for each core.
> +		 *
> +		 * This waiting mechanism is necessary because
> +		 * rproc_auto_boot_callback() for core1 can be called before
> +		 * core0 due to thread execution order.
> +		 */
> +		ret = wait_event_interruptible_timeout(cluster->core_transition,
> +						       core->released_from_reset,
> +						       msecs_to_jiffies(2000));
> +		if (ret <= 0) {
> +			dev_err(dev,
> +				"Timed out waiting for %s core to power up!\n",
> +				rproc->name);
> +			return ret;
> +		}
>  	}
>  
>  	return 0;
> @@ -1709,6 +1736,7 @@ static int k3_r5_probe(struct platform_device *pdev)
>  	cluster->dev = dev;
>  	cluster->soc_data = data;
>  	INIT_LIST_HEAD(&cluster->cores);
> +	init_waitqueue_head(&cluster->core_transition);
>  
>  	ret = of_property_read_u32(np, "ti,cluster-mode", &cluster->mode);
>  	if (ret < 0 && ret != -EINVAL) {
> -- 
> 2.34.1
>