Re: [PATCH] remoteproc: k3-r5: Wait for core0 power-up before powering up core1

[Mathieu Poirier]

On Wed, 4 Oct 2023 at 07:51, Apurva Nandan <a-nandan@xxxxxx> wrote:
>
> Hi Mathieu,
>
> On 11/09/23 22:15, Mathieu Poirier wrote:
> > Hi Apurva,
> >
> > On Wed, Sep 06, 2023 at 06:17:56PM +0530, Apurva Nandan wrote:
> >> 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@xxxxxx>
> >> ---
> >>
> >>   kpv report: https://gist.githubusercontent.com/apurvanandan1997/feb3b304121c265b7827be43752b7ae8/raw
> >>
> >>   drivers/remoteproc/ti_k3_r5_remoteproc.c | 23 +++++++++++++++++++++++
> >>   1 file changed, 23 insertions(+)
> >>
> >> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> >> index ad3415a3851b..ba5e503f7c9c 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;
> >>      ret = ti_sci_proc_get_status(core->tsp, &boot_vec, &cfg, &ctrl,
> >>                                   &stat);
> >>      if (ret < 0) {
> >> @@ -1280,6 +1287,21 @@ 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.
> >> +             */
> > Wrong multi-line comment format.
> Okay will fix this.
> >> +            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;
> >> +            }
> >  From my perspective, this is needed because rproc_auto_boot_callback() for core1
> > can be called before core0 due to thread execution order.  Am I correct?
> Yes
> > If so please add this explanation to the comment you have above.  Also, let's
> > say a user decides to switch both cores off after reboot.  At that time, what
> > prevents a user from switching on core1 before core0 via sysfs?
> Okay, will add the explanation.
> Currently, adding support for graceful shutdown is in progress. As of
> now in order
> to stop/start core or change firmware, we recommend users to restart the
> OS.

You will need to address access via debugfs and sysfs if you want this
patch to move forward.

> > Thanks,
> > Mathieu
> >
> >>      }
> >>
> >>      return 0;
> >> @@ -1709,6 +1731,7 @@ 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
> >>