Re: [PATCH 4/4] remoteproc: k3-r5: support for graceful stop of remote cores

Richard GENOUD
2024-07-01T16:48:41Z

Le 29/06/2024 à 00:50, Andrew Davis a écrit :
> On 6/21/24 10:00 AM, Richard Genoud wrote:
>> Introduce software IPC handshake between the K3-R5 remote proc driver
>> and the R5 MCU to gracefully stop/reset the remote core.
>>
>> Upon a stop request, K3-R5 remote proc driver sends a RP_MBOX_SHUTDOWN
>> mailbox message to the remote R5 core.
>> The remote core is expected to:
>> - relinquish all the resources acquired through Device Manager (DM)
>> - disable its interrupts
>> - send back a mailbox acknowledgment RP_MBOX_SHUDOWN_ACK
>> - enter WFI state.
>>
>> Meanwhile, the K3-R5 remote proc driver does:
>> - wait for the RP_MBOX_SHUTDOWN_ACK from the remote core
>> - wait for the remote proc to enter WFI state
>> - reset the remote core through device manager
>>
>> Based on work from: Hari Nagalla <hnagalla@ti.com>
>>
>> Signed-off-by: Richard Genoud <richard.genoud@bootlin.com>
>> ---
>>   drivers/remoteproc/omap_remoteproc.h     |  9 +++++-
>>   drivers/remoteproc/ti_k3_r5_remoteproc.c | 40 ++++++++++++++++++++++++
>>   2 files changed, 48 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/remoteproc/omap_remoteproc.h
>> b/drivers/remoteproc/omap_remoteproc.h
>> index 828e13256c02..c008f11fa2a4 100644
>> --- a/drivers/remoteproc/omap_remoteproc.h
>> +++ b/drivers/remoteproc/omap_remoteproc.h
>> @@ -42,6 +42,11 @@
>>    * @RP_MBOX_SUSPEND_CANCEL: a cancel suspend response from a remote
>> processor
>>    * on a suspend request
>>    *
>> + * @RP_MBOX_SHUTDOWN: shutdown request for the remote processor
>> + *
>> + * @RP_MBOX_SHUTDOWN_ACK: successful response from remote processor
>> for a
>> + * shutdown request. The remote processor should be in WFI state
>> short after.
>> + *
>>    * Introduce new message definitions if any here.
>>    *
>>    * @RP_MBOX_END_MSG: Indicates end of known/defined messages from
>> remote core
>> @@ -59,7 +64,9 @@ enum omap_rp_mbox_messages {
>>       RP_MBOX_SUSPEND_SYSTEM    = 0xFFFFFF11,
>>       RP_MBOX_SUSPEND_ACK    = 0xFFFFFF12,
>>       RP_MBOX_SUSPEND_CANCEL    = 0xFFFFFF13,
>> -    RP_MBOX_END_MSG        = 0xFFFFFF14,
>> +    RP_MBOX_SHUTDOWN    = 0xFFFFFF14,
>> +    RP_MBOX_SHUTDOWN_ACK    = 0xFFFFFF15,
>> +    RP_MBOX_END_MSG        = 0xFFFFFF16,
>>   };
>>   #endif /* _OMAP_RPMSG_H */
>> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> index a2ead87952c7..918a15e1dd9a 100644
>> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
>> @@ -21,6 +21,7 @@
>>   #include <linux/pm_runtime.h>
>>   #include <linux/remoteproc.h>
>>   #include <linux/suspend.h>
>> +#include <linux/iopoll.h>
>>   #include <linux/reset.h>
>>   #include <linux/slab.h>
>> @@ -172,8 +173,23 @@ struct k3_r5_rproc {
>>       struct k3_r5_core *core;
>>       struct k3_r5_mem *rmem;
>>       int num_rmems;
>> +    struct completion shutdown_complete;
>>   };
>> +/*
>> + * This will return true if the remote core is in Wait For Interrupt
>> state.
>> + */
>> +static bool k3_r5_is_core_in_wfi(struct k3_r5_core *core)
>> +{
>> +    int ret;
>> +    u64 boot_vec;
>> +    u32 cfg, ctrl, stat;
>> +
>> +    ret = ti_sci_proc_get_status(core->tsp, &boot_vec, &cfg, &ctrl,
>> &stat);
>> +
>> +    return !ret ? !!(stat & PROC_BOOT_STATUS_FLAG_R5_WFI) : false;
>
> Too fancy for me :) Just return if (ret) right after get_status().
Ok, too much punctuation :)

>
> Looks like this function is called in a polling loop, if
> ti_sci_proc_get_status() fails once, it won't get better,
> no need to keep checking, we should just error out of
> the polling loop.
Ok

Thanks !
>
> Andrew
>
>> +}
>> +
>>   /**
>>    * k3_r5_rproc_mbox_callback() - inbound mailbox message handler
>>    * @client: mailbox client pointer used for requesting the mailbox
>> channel
>> @@ -209,6 +225,10 @@ static void k3_r5_rproc_mbox_callback(struct
>> mbox_client *client, void *data)
>>       case RP_MBOX_ECHO_REPLY:
>>           dev_info(dev, "received echo reply from %s\n", name);
>>           break;
>> +    case RP_MBOX_SHUTDOWN_ACK:
>> +        dev_dbg(dev, "received shutdown_ack from %s\n", name);
>> +        complete(&kproc->shutdown_complete);
>> +        break;
>>       default:
>>           /* silently handle all other valid messages */
>>           if (msg >= RP_MBOX_READY && msg < RP_MBOX_END_MSG)
>> @@ -634,6 +654,7 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>>       struct k3_r5_cluster *cluster = kproc->cluster;
>>       struct device *dev = kproc->dev;
>>       struct k3_r5_core *core1, *core = kproc->core;
>> +    bool wfi;
>>       int ret;
>> @@ -650,6 +671,24 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
>>           }
>>       }
>> +    /* Send SHUTDOWN message to remote proc */
>> +    reinit_completion(&kproc->shutdown_complete);
>> +    ret = mbox_send_message(kproc->mbox, (void *)RP_MBOX_SHUTDOWN);
>> +    if (ret < 0) {
>> +        dev_err(dev, "Sending SHUTDOWN message failed: %d. Halting
>> core anyway.\n", ret);
>> +    } else {
>> +        ret = wait_for_completion_timeout(&kproc->shutdown_complete,
>> +                          msecs_to_jiffies(1000));
>> +        if (ret == 0) {
>> +            dev_err(dev, "Timeout waiting SHUTDOWN_ACK message.
>> Halting core anyway.\n");
>> +        } else {
>> +            ret = readx_poll_timeout(k3_r5_is_core_in_wfi, core,
>> +                         wfi, wfi, 200, 2000);
>> +            if (ret)
>> +                dev_err(dev, "Timeout waiting for remote proc to be
>> in WFI state. Halting core anyway.\n");
>> +        }
>> +    }
>> +
>>       /* halt all applicable cores */
>>       if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
>>           list_for_each_entry(core, &cluster->cores, elem) {
>> @@ -1410,6 +1449,7 @@ static int k3_r5_cluster_rproc_init(struct
>> platform_device *pdev)
>>               goto err_config;
>>           }
>> +        init_completion(&kproc->shutdown_complete);
>>   init_rmem:
>>           k3_r5_adjust_tcm_sizes(kproc);
>>