linux-kernel - Re: [PATCH] remoteproc: k3-r5: Decouple firmware booting from probe routine

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Message-ID: <56b63a39-ea4d-4edf-9295-ca28c83655c8@ti.com>
Date: Sat, 7 Sep 2024 15:41:38 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: Beleswar Padhi <b-padhi@...com>, <andersson@...nel.org>,
        <mathieu.poirier@...aro.org>
CC: <afd@...com>, <hnagalla@...com>, <s-anna@...com>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] remoteproc: k3-r5: Decouple firmware booting from probe
 routine


On 9/6/2024 3:10 PM, Beleswar Padhi wrote:
> The current implementation of the waiting mechanism in probe() waits for
> the 'released_from_reset' flag to be set which is done in
> k3_r5_rproc_prepare() as part of rproc_fw_boot(). This causes unexpected
> failures in cases where the firmware is unavailable at boot time,
> resulting in probe failure and removal of the remoteproc handles in the
> sysfs paths.

I won't say failure, I will say this is behavior of driver.

Driver expect firmware to be available , but I agree driver should be 
able to execute

with/without firmware availability.


> To address this, the waiting mechanism is refactored out of the probe
> routine into the appropriate k3_r5_rproc_prepare/unprepare() and
> k3_r5_rproc_start/stop() functions. This allows the probe routine to
> complete without depending on firmware booting, while still maintaining
> the required power-synchronization between cores.
>
> Fixes: 61f6f68447ab ("remoteproc: k3-r5: Wait for core0 power-up before powering up core1")
> Signed-off-by: Beleswar Padhi <b-padhi@...com>
> ---
> Posted this as a Fix as this was breaking usecases where we wanted to load a
> firmware by writing to sysfs handles in userspace.
>
>   drivers/remoteproc/ti_k3_r5_remoteproc.c | 170 ++++++++++++++++-------
>   1 file changed, 118 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> [..]
> +	core0 = list_first_entry(&cluster->cores, struct k3_r5_core, elem);
> +	core1 = list_last_entry(&cluster->cores, struct k3_r5_core, elem);
> +	if (cluster->mode == CLUSTER_MODE_SPLIT && core == core1 &&
> +	    core0->released_from_reset == false) {
> +		ret = wait_event_interruptible_timeout(cluster->core_transition,
> +						       core0->released_from_reset,
> +						       msecs_to_jiffies(2000));
only one wait in start should be good enough,
> +		if (ret <= 0) {
> +			dev_err(dev, "can not power up core1 before core0");
> +			return -EPERM;
> +		}
> +	}
> +
>   	ret = ti_sci_proc_get_status(core->tsp, &boot_vec, &cfg, &ctrl, &stat);
>   	if (ret < 0)
>   		return ret;
> @@ -470,6 +492,12 @@ static int k3_r5_rproc_prepare(struct rproc *rproc)
>   		return ret;
>   	}
>   
> +	/* Notify all threads in the wait queue when core state has changed so
> +	 * that threads waiting for this condition can be executed.
> +	 */
> +	core->released_from_reset = true;
> +	wake_up_interruptible(&cluster->core_transition);
> +
>   	/*
>   	 * Newer IP revisions like on J7200 SoCs support h/w auto-initialization
>   	 * of TCMs, so there is no need to perform the s/w memzero. This bit is
> @@ -515,14 +543,46 @@ static int k3_r5_rproc_unprepare(struct rproc *rproc)
>   {
>   	struct k3_r5_rproc *kproc = rproc->priv;
>   	struct k3_r5_cluster *cluster = kproc->cluster;
> -	struct k3_r5_core *core = kproc->core;
> +	struct k3_r5_core *core0, *core1, *core = kproc->core;


why you need wait in unprepare/stop,

In case you are failing during firmware load or so then already we are 
in bad state.

if this is call from user land then, i don't except anyone will auto 
trigger stopping of core-0

IMO, in unprepare/stop, if action is attempted on core1 with core-0 ON, 
simply return error.


> [..]
> @@ -629,7 +702,7 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>   	struct k3_r5_rproc *kproc = rproc->priv;
>   	struct k3_r5_cluster *cluster = kproc->cluster;
>   	struct device *dev = kproc->dev;
>