On Thu, 15 Jan 2026 at 03:36, Mathieu Poirier
<[email protected]> wrote:
>
> On Tue, 13 Jan 2026 at 09:37, Beleswar Prasad Padhi <[email protected]> wrote:
> >
> > Hi Mathieu,
> >
> > Sorry for the delay in response here. Somehow all the messages
> > in this thread ended up in spam. Didn't realize there were new
> > msgs until I looked up on lore.
> >
>
> I've been getting weird automated email replies from TI.
>
> > On 17/12/25 03:53, Mathieu Poirier wrote:
> > > Hi Beleswar,
> > >
> > > On Tue, Nov 25, 2025 at 02:07:46PM +0530, Beleswar Padhi wrote:
> > >> From: Richard Genoud <[email protected]>
> > >>
> > >> Introduce software IPC handshake between the host running Linux and the
> > >> remote processors to gracefully stop/reset the remote core.
> > >>
> > >> Upon a stop request, remoteproc driver sends a RP_MBOX_SHUTDOWN mailbox
> > >> message to the remotecore.
> > >> 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 remoteproc driver does:
> > >> - wait for the RP_MBOX_SHUTDOWN_ACK from the remote core
> > >> - wait for the remoteproc to enter WFI state
> > >> - reset the remote core through device manager
> > >>
> > >> Based on work from: Hari Nagalla <[email protected]>
> > >>
> > >> Signed-off-by: Richard Genoud <[email protected]>
> > >> [[email protected]: Extend support to all rprocs]
> > >> Signed-off-by: Beleswar Padhi <[email protected]>
> > >> ---
> > >> v2: Changelog:
> > >> 1. Extend graceful shutdown support for all rprocs (R5, DSP, M4)
> > >> 2. Halt core only if SHUTDOWN_ACK is received from rproc and it has
> > >> entered WFI state.
> > >> 3. Convert return type of is_core_in_wfi() to bool. Works better with
> > >> readx_poll_timeout() condition.
> > >> 4. Cast RP_MBOX_SHUTDOWN to uintptr_t to suppress compiler warnings
> > >> when void* is 64 bit.
> > >> 5. Wrapped Graceful shutdown code in the form of notify_shutdown_rproc
> > >> function.
> > >> 6. Updated commit message to fix minor typos and such.
> > >>
> > >> Link to v1:
> > >> https://lore.kernel.org/all/[email protected]/
> > >>
> > >> Testing done:
> > >> 1. Tested Boot across all TI K3 EVM/SK boards.
> > >> 2. Tested IPC on all TI K3 J7* EVM/SK boards (& AM62x SK).
> > >> 4. Tested R5 rprocs can now be shutdown and powered back on
> > >> from userspace.
> > >> 3. Tested that each patch in the series generates no new
> > >> warnings/errors.
> > >>
> > >> drivers/remoteproc/omap_remoteproc.h | 9 ++-
> > >> drivers/remoteproc/ti_k3_common.c | 72 +++++++++++++++++++++++
> > >> drivers/remoteproc/ti_k3_common.h | 4 ++
> > >> drivers/remoteproc/ti_k3_dsp_remoteproc.c | 2 +
> > >> drivers/remoteproc/ti_k3_m4_remoteproc.c | 2 +
> > >> drivers/remoteproc/ti_k3_r5_remoteproc.c | 5 ++
> > >> 6 files changed, 93 insertions(+), 1 deletion(-)
> > >>
> > >> diff --git a/drivers/remoteproc/omap_remoteproc.h
> > >> b/drivers/remoteproc/omap_remoteproc.h
> > >> index 828e13256c023..c008f11fa2a43 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_common.c
> > >> b/drivers/remoteproc/ti_k3_common.c
> > >> index 56b71652e449f..5d469f65115c3 100644
> > >> --- a/drivers/remoteproc/ti_k3_common.c
> > >> +++ b/drivers/remoteproc/ti_k3_common.c
> > >> @@ -18,7 +18,9 @@
> > >> * Hari Nagalla <[email protected]>
> > >> */
> > >>
> > >> +#include <linux/delay.h>
> > >> #include <linux/io.h>
> > >> +#include <linux/iopoll.h>
> > >> #include <linux/mailbox_client.h>
> > >> #include <linux/module.h>
> > >> #include <linux/of_address.h>
> > >> @@ -69,6 +71,10 @@ void k3_rproc_mbox_callback(struct mbox_client
> > >> *client, void *data)
> > >> case RP_MBOX_ECHO_REPLY:
> > >> dev_info(dev, "received echo reply from %s\n", rproc->name);
> > >> break;
> > >> + case RP_MBOX_SHUTDOWN_ACK:
> > >> + dev_dbg(dev, "received shutdown_ack from %s\n",
> > >> rproc->name);
> > >> + complete(&kproc->shutdown_complete);
> > >> + break;
> > >> default:
> > >> /* silently handle all other valid messages */
> > >> if (msg >= RP_MBOX_READY && msg < RP_MBOX_END_MSG)
> > >> @@ -188,6 +194,67 @@ int k3_rproc_request_mbox(struct rproc *rproc)
> > >> }
> > >> EXPORT_SYMBOL_GPL(k3_rproc_request_mbox);
> > >>
> > >> +/**
> > >> + * is_core_in_wfi - Utility function to check core status
> > >> + * @kproc: remote core pointer used for checking core status
> > >> + *
> > >> + * This utility function is invoked by the shutdown sequence to ensure
> > >> + * the remote core is in wfi, before asserting a reset.
> > >> + */
> > >> +bool is_core_in_wfi(struct k3_rproc *kproc)
> > >> +{
> > >> + int ret;
> > >> + u64 boot_vec;
> > >> + u32 cfg, ctrl, stat;
> > >> +
> > >> + ret = ti_sci_proc_get_status(kproc->tsp, &boot_vec, &cfg, &ctrl,
> > >> &stat);
> > >> + if (ret)
> > >> + return false;
> > >> +
> > >> + return (bool)(stat & PROC_BOOT_STATUS_FLAG_CPU_WFI);
> > >> +}
> > >> +EXPORT_SYMBOL_GPL(is_core_in_wfi);
> > >> +
> > >> +/**
> > >> + * notify_shutdown_rproc - Prepare the remoteproc for a shutdown
> > >> + * @kproc: remote core pointer used for sending mbox msg
> > >> + *
> > >> + * This function sends the shutdown prepare message to remote processor
> > >> and
> > >> + * waits for an ACK. Further, it checks if the remote processor has
> > >> entered
> > >> + * into WFI mode. It is invoked in shutdown sequence to ensure the rproc
> > >> + * has relinquished its resources before asserting a reset, so the
> > >> shutdown
> > >> + * happens cleanly.
> > >> + */
> > >> +int notify_shutdown_rproc(struct k3_rproc *kproc)
> > >> +{
> > >> + bool wfi_status = false;
> > >> + int ret;
> > >> +
> > >> + reinit_completion(&kproc->shutdown_complete);
> > >> +
> > >> + ret = mbox_send_message(kproc->mbox, (void
> > >> *)(uintptr_t)RP_MBOX_SHUTDOWN);
> > >> + if (ret < 0) {
> > >> + dev_err(kproc->dev, "PM mbox_send_message failed: %d\n",
> > >> ret);
> > >> + return ret;
> > >> + }
> > >> +
> > >> + ret = wait_for_completion_timeout(&kproc->shutdown_complete,
> > >> + msecs_to_jiffies(5000));
> > >> + if (ret == 0) {
> > >> + dev_err(kproc->dev, "%s: timeout waiting for rproc
> > >> completion event\n",
> > >> + __func__);
> > >> + return -EBUSY;
> > >> + }
> > >> +
> > >
> > > Won't that create an issue on systems with an older FW that doesn't send a
> > > RP_MBOX_SHUDOWN_ACK message? Unless I'm missing something, this kind of
> > > feature
> > > needs to be backward compatible.
> >
> >
> > I feel it would be unsafe to just abruptly power off a core without some
> > handshake.. The core could be executing something, there could be
> > pending bus transactions leading to system hangs etc.. We start the
> > IPC mechanism with a handshake, so we should end it with a
> > handshake too.. And for firmwares that don't support this handshake,
> > IMO its better to reject the shutdown request. What do you think?
> >
>
> We can't affect the behavior of systems where old FW is coupled with a
> new kernel. If people want to address the bugs you referred to, they
> can update their FW as they see fit. As such things need to be
> backward compatible. NXP has recently implemented a handshake
> mechanism such as this, but to assert the readiness of a booting
> remote processor. They used the vendor specific resource table to
> store a flag that enables the handshake - I suggest using the same
> heuristic to implement this feature.
A flag in a resource table enabling the new behaviour could work, but
we would probably need another way to do the new thing, maybe with a
devicetree flag. Why? Because people are running TI's kernel, which
has had this feature since Feb 2025, and may want to migrate to a
mainline kernel. Those firmwares already use the handshake.
If we want to be nice to existing users, we should provide a way to be
compatible with existing firmwares which don't support
RP_MBOX_SHUTDOWN, and with existing firmwares which do.
That said, restarting remote processors on k3 was quite broken without
the shutdown handshake, often leading to hangs/crashes requiring a
full system reboot to recover. This is why I previously asked about
recovery if the remoteproc crashes or is unable to handle the shutdown
request.
I suspect that most real world users who are actually restarting
remoteprocs on k3 are already using the handshake with TI's kernel.
IMHO it's probably fine to just send RP_MBOX_SHUTDOWN to firmwares
which don't support it, and handle old firmwares via the same recovery
path as new firmwares which have crashed. This would mean that
upgrading a system with an old firmware to a new kernel will have an
additional delay when shutting down a remoteproc, but realistically,
this shutdown path was broken anyway.
Patrick
> > For older TI firmwares also, doing rproc_stop() resulted in those
> > intermittent bugs as mentioned above. So we never really supported
> > the stop() feature until now.
> >
> > Thanks,
> > Beleswar
> >
> > >
> > > Thanks,
> > > Mathieu
> > >
> > >> + ret = readx_poll_timeout(is_core_in_wfi, kproc, wfi_status,
> > >> wfi_status,
> > >> + 200, 2000);
> > >> + if (ret)
> > >> + return ret;
> > >> +
> > >> + return 0;
> > >> +}
> > >> +EXPORT_SYMBOL_GPL(notify_shutdown_rproc);
> > >> +
> > >> /*
> > >> * The K3 DSP and M4 cores have a local reset that affects only the
> > >> CPU, and a
> > >> * generic module reset that powers on the device and allows the
> > >> internal
> > >> @@ -288,6 +355,11 @@ EXPORT_SYMBOL_GPL(k3_rproc_start);
> > >> int k3_rproc_stop(struct rproc *rproc)
> > >> {
> > >> struct k3_rproc *kproc = rproc->priv;
> > >> + int ret;
> > >> +
> > >> + ret = notify_shutdown_rproc(kproc);
> > >> + if (ret)
> > >> + return ret;
> > >>
> > >> return k3_rproc_reset(kproc);
> > >> }
> > >> diff --git a/drivers/remoteproc/ti_k3_common.h
> > >> b/drivers/remoteproc/ti_k3_common.h
> > >> index aee3c28dbe510..2a025f4894b82 100644
> > >> --- a/drivers/remoteproc/ti_k3_common.h
> > >> +++ b/drivers/remoteproc/ti_k3_common.h
> > >> @@ -22,6 +22,7 @@
> > >> #define REMOTEPROC_TI_K3_COMMON_H
> > >>
> > >> #define KEYSTONE_RPROC_LOCAL_ADDRESS_MASK (SZ_16M - 1)
> > >> +#define PROC_BOOT_STATUS_FLAG_CPU_WFI 0x00000002
> > >>
> > >> /**
> > >> * struct k3_rproc_mem - internal memory structure
> > >> @@ -92,6 +93,7 @@ struct k3_rproc {
> > >> u32 ti_sci_id;
> > >> struct mbox_chan *mbox;
> > >> struct mbox_client client;
> > >> + struct completion shutdown_complete;
> > >> void *priv;
> > >> };
> > >>
> > >> @@ -115,4 +117,6 @@ int k3_rproc_of_get_memories(struct platform_device
> > >> *pdev,
> > >> void k3_mem_release(void *data);
> > >> int k3_reserved_mem_init(struct k3_rproc *kproc);
> > >> void k3_release_tsp(void *data);
> > >> +bool is_core_in_wfi(struct k3_rproc *kproc);
> > >> +int notify_shutdown_rproc(struct k3_rproc *kproc);
> > >> #endif /* REMOTEPROC_TI_K3_COMMON_H */
> > >> diff --git a/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> > >> b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> > >> index d6ceea6dc920e..156ae09d8ee25 100644
> > >> --- a/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> > >> +++ b/drivers/remoteproc/ti_k3_dsp_remoteproc.c
> > >> @@ -133,6 +133,8 @@ static int k3_dsp_rproc_probe(struct platform_device
> > >> *pdev)
> > >> if (ret)
> > >> return ret;
> > >>
> > >> + init_completion(&kproc->shutdown_complete);
> > >> +
> > >> ret = k3_rproc_of_get_memories(pdev, kproc);
> > >> if (ret)
> > >> return ret;
> > >> diff --git a/drivers/remoteproc/ti_k3_m4_remoteproc.c
> > >> b/drivers/remoteproc/ti_k3_m4_remoteproc.c
> > >> index 3a11fd24eb52b..64d99071279b0 100644
> > >> --- a/drivers/remoteproc/ti_k3_m4_remoteproc.c
> > >> +++ b/drivers/remoteproc/ti_k3_m4_remoteproc.c
> > >> @@ -90,6 +90,8 @@ static int k3_m4_rproc_probe(struct platform_device
> > >> *pdev)
> > >> if (ret)
> > >> return ret;
> > >>
> > >> + init_completion(&kproc->shutdown_complete);
> > >> +
> > >> ret = k3_rproc_of_get_memories(pdev, kproc);
> > >> if (ret)
> > >> return ret;
> > >> diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > >> b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > >> index 04f23295ffc10..8748dc6089cc2 100644
> > >> --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > >> +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > >> @@ -533,6 +533,10 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
> > >> struct k3_r5_cluster *cluster = core->cluster;
> > >> int ret;
> > >>
> > >> + ret = notify_shutdown_rproc(kproc);
> > >> + if (ret)
> > >> + return ret;
> > >> +
> > >> /* halt all applicable cores */
> > >> if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
> > >> list_for_each_entry(core, &cluster->cores, elem) {
> > >> @@ -1129,6 +1133,7 @@ static int k3_r5_cluster_rproc_init(struct
> > >> platform_device *pdev)
> > >> goto out;
> > >> }
> > >>
> > >> + init_completion(&kproc->shutdown_complete);
> > >> init_rmem:
> > >> k3_r5_adjust_tcm_sizes(kproc);
> > >>
> > >> --
> > >> 2.34.1
> > >>
>
