On 9/30/2026 11:27 AM, Mathieu Poirier wrote:
> Hi,
>
> On Thu, Sep 24, 2026 at 01:34:09PM -0700, Tanmay Shah wrote:
>> On AMD-Xilinx platforms cortex-A and cortex-R can be configured as
>> separate subsystems. In this case, both cores can boot independent of
>> each other. This is platform management firmware configuration to manage
>
> I'm not sure to understand what the above sentence adds to the changelog. I
> suggest either reworking or removing.
>
Ack, I will remove it.
>> cores. In such a configuration, if Linux went through an uncontrolled
>> reboot during active rpmsg communication, then during next boot it can
>> find rpmsg virtio status not in the reset state. In such case it is
>> important to reset the virtio status during attach callback and wait
>> for the remote to handle virtio device reset. After reset, the remote
>> is expected to generate the notification to the host or the host will
>> eventually timeout and continue the normal boot flow.
>>
>> Assisted-by: LLM
>> Signed-off-by: Tanmay Shah <[email protected]>
>> ---
>> drivers/remoteproc/xlnx_r5_remoteproc.c | 74 +++++++++++++++++++++++++
>> 1 file changed, 74 insertions(+)
>>
>> diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c
>> b/drivers/remoteproc/xlnx_r5_remoteproc.c
>> index 630621288430..6e7e2a5ea83c 100644
>> --- a/drivers/remoteproc/xlnx_r5_remoteproc.c
>> +++ b/drivers/remoteproc/xlnx_r5_remoteproc.c
>> @@ -6,6 +6,7 @@
>>
>> #include <linux/dma-mapping.h>
>> #include <linux/firmware/xlnx-zynqmp.h>
>> +#include <linux/jiffies.h>
>> #include <linux/kernel.h>
>> #include <linux/mailbox_client.h>
>> #include <linux/mailbox/zynqmp-ipi-message.h>
>> @@ -15,6 +16,7 @@
>> #include <linux/of_reserved_mem.h>
>> #include <linux/platform_device.h>
>> #include <linux/remoteproc.h>
>> +#include <linux/wait.h>
>>
>> #include "remoteproc_internal.h"
>>
>> @@ -33,6 +35,8 @@
>> #define RSC_TBL_XLNX_MAGIC ((uint32_t)'x' << 24 | (uint32_t)'a' << 16 | \
>> (uint32_t)'m' << 8 | (uint32_t)'p')
>>
>> +#define RPROC_ATTACH_TIMEOUT_US (1000 * 1000)
>> +
>
> Please see if you can use a kernel defined time constant instead of minting
> your
> own.
>
Ack.
>> /*
>> * settings for RPU cluster mode which
>> * reflects possible values of xlnx,cluster-mode dt-property
>> @@ -167,6 +171,9 @@ struct xlnx_rproc_crash_report {
>> * @rsc_tbl_size: resource table size retrieved from remote
>> * @pm_domain_id: RPU CPU power domain id
>> * @ipi: pointer to mailbox information
>> + * @attach_wq: wait queue for attach-time vdev reset acknowledgment
>
> I don't understand the explanation for @attach_wq - please rework.
>
>> + * @waiting_for_attach_ack: whether attach is waiting for remote interrupt
>> + * @attach_ack: remote interrupt observed while attach wait is active
>> */
>> struct zynqmp_r5_core {
>> struct xlnx_rproc_crash_report *crash_report;
>> @@ -181,6 +188,9 @@ struct zynqmp_r5_core {
>> u32 rsc_tbl_size;
>> u32 pm_domain_id;
>> struct mbox_info *ipi;
>> + wait_queue_head_t attach_wq;
>> + bool waiting_for_attach_ack;
>> + bool attach_ack;
>> };
>>
>> /**
>> @@ -270,10 +280,17 @@ static void handle_event_notified(struct work_struct
>> *work)
>> static void zynqmp_r5_mb_rx_cb(struct mbox_client *cl, void *msg)
>> {
>> struct zynqmp_ipi_message *ipi_msg, *buf_msg;
>> + struct zynqmp_r5_core *r5_core;
>> struct mbox_info *ipi;
>> size_t len;
>>
>> ipi = container_of(cl, struct mbox_info, mbox_cl);
>> + r5_core = ipi->r5_core;
>
> Is there really a chance that ipi->r5_core be NULL?
>
Recently, INIT_WORK was moved before
mbox_request_channel_byname(mbox_cl, "rx"), In this case, if interrupt
occurs between requesting "rx" channel, and assigning r5_cores to ipi,
then r5_core can be NULL.
>> +
>> + if (r5_core && READ_ONCE(r5_core->waiting_for_attach_ack)) {
>> + WRITE_ONCE(r5_core->attach_ack, true);
>
> Why use READ_ONCE/WRITE_ONCE here - what does it give you?
>
I think this was added by AI agent, and I think it is to maintain atomic
nature of variable access. But if you prefer to protect these variables
via locks I will do that. These variables are shared between attach()
context and IPI interrupt, so I think they should be protected somehow.
>> + wake_up(&r5_core->attach_wq);
>> + }
>
> If @rsc->status has been set to 0 in zynqmp_r5_attach() and an IPI is received
> before ->kick(), the core may erroneously think the remote processor is
> acknowleging the reset.
>
Ack. Probably need to set these flags after kick(). I will do that.
>>
>> /* copy data from ipi buffer to r5_core if IPI is buffered. */
>> ipi_msg = (struct zynqmp_ipi_message *)msg;
>> @@ -820,6 +837,62 @@ static int zynqmp_r5_get_rsc_table_va(struct
>> zynqmp_r5_core *r5_core)
>>
>> static int zynqmp_r5_attach(struct rproc *rproc)
>> {
>> + struct zynqmp_r5_core *r5_core = rproc->priv;
>> + struct device *dev = &rproc->dev;
>> + bool wait_for_remote = false;
>> + struct fw_rsc_vdev *rsc;
>> + struct fw_rsc_hdr *hdr;
>> + int i, offset, avail;
>> + long time_left;
>> +
>> + if (!rproc->table_ptr)
>> + goto attach_success;
>> +
>> + for (i = 0; i < rproc->table_ptr->num; i++) {
>> + offset = rproc->table_ptr->offset[i];
>> + hdr = (void *)rproc->table_ptr + offset;
>> + avail = rproc->table_sz - offset - sizeof(*hdr);
>> + rsc = (void *)hdr + sizeof(*hdr);
>> +
>> + /* make sure table isn't truncated */
>> + if (avail < 0) {
>> + dev_err(dev, "rsc table is truncated\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (hdr->type != RSC_VDEV)
>> + continue;
>> +
>> + /*
>> + * reset vdev status, in case previous run didn't leave it in
>> + * a clean state.
>> + */
>> + if (rsc->status) {
>> + rsc->status = 0;
>> + wait_for_remote = true;
>> + break;
>> + }
>> + }
>> +
>> + if (wait_for_remote) {
>> + WRITE_ONCE(r5_core->attach_ack, false);
>> + WRITE_ONCE(r5_core->waiting_for_attach_ack, true);
>> + }
>
> Again, I would like to understand the motivation behind using WRITE_ONCE()
> here... I just don't see what kind of re-ordering issue you need to guard
> against.
>
Ack. I will remove and introduce locks if that plan works.
>> +
>> + /* kick remote to notify about attach */
>> + rproc->ops->kick(rproc, 0);
>
> Will older FW be able to deal with this properly?
>
>> +
>> + if (wait_for_remote) {
>> + time_left = wait_event_timeout(r5_core->attach_wq,
>> + READ_ONCE(r5_core->attach_ack),
>> +
>> usecs_to_jiffies(RPROC_ATTACH_TIMEOUT_US));
>
> The condition where the driver is removed or the remoteproc shut down needs
> also
> needs to be handled as a break out condition.
>
So this whole feature will be helpful only if linux gets rebooted
without proper cleanup. If driver is removed, it will call detach() via
zynqmp_cluster_exit(). If machine goes throug 'reboot' command, then the
driver has 'shutdown' callback registered which will call 'detach()'
operation. In these cases the remoteproc reset is guranteed and the
status will be 0 on next boot.
But if linux didn't get chance to execute above callbacks, only then the
status will be left non-zero on reboot.
> Thanks,
> Mathieu
>
>> + WRITE_ONCE(r5_core->waiting_for_attach_ack, false);
>> +
>> + if (!time_left)
>> + dev_warn(dev, "timeout waiting for remote vdev reset
>> ack\n");
>> + }
>> +
>> +attach_success:
>> dev_dbg(&rproc->dev, "rproc %d attached\n", rproc->index);
>>
>> return 0;
>> @@ -920,6 +993,7 @@ static struct zynqmp_r5_core
>> *zynqmp_r5_alloc_rproc_core(struct device *cdev)
>> r5_core = r5_rproc->priv;
>> r5_core->dev = cdev;
>> r5_core->np = dev_of_node(cdev);
>> + init_waitqueue_head(&r5_core->attach_wq);
>> if (!r5_core->np) {
>> dev_err(cdev, "can't get device node for r5 core\n");
>> ret = -EINVAL;
>>
>> base-commit: 5f639b3018c0026a5341949724b4b921cf3a3d5d
>> --
>> 2.43.0
>>
