On Mon, Mar 30, 2026 at 01:43:03PM -0500, Shah, Tanmay wrote: > Hello, > > Thanks for the reviews. Please find my comments below: > > On 3/27/2026 2:58 PM, Mathieu Poirier wrote: > > On Tue, Mar 17, 2026 at 01:12:51PM -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. If Linux went through 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 sometime for the > >> remote to handle virtio driver reset. > > > > I understand the user case, but won't that situation happen regardless of > > whether cores operate sync or split mode? > > > > I want to make it clear that this is not same as Cortex-R cluster > configured as lockstep vs split mode. > > This is different configuration between Cortex-A cores and Cortex-R > cores. It is a firmware driver configuration of how it treats cortex-A > and Cortex-R subsystems. > > In the firmware driver, we can configure Cortex-A cluster as owner of > Cortex-R cluster, and in that case, if Cortex-A reboots, the firmware > will also reboot cortex-R cores. This policy makes Cortex-A as owner of > Cortex-R cores. In this configuraton this patch is not needed, because > if Cortex-A reboots then platform management firmware will also reboot > Cortex-R cores as well and vdev status flag will be always 0. > > In another configuration in the firmware driver, Cortex-R cores can be > independent of Cortex-A cores. This means, Cortex-A is not the owner of > the Cortex-R cores. Both are independent subsystem. Only in this > configuration, this patch applies because it is possible that Cortex-A > reboots while Cortex-R doesn't and Cortex-R still runs as it is. > > So only in the second type of configuration, this patch is needed when > COrtex-A running linux reboots and when driver probes and tries to > attach it can find that vdev flag is not reset. In the first > configuartion if linux reboots, then It's guranteed that vdev status > flag will always be in the reset state. > > If you prefer I can extend the commit message with all above details or > put as comment in the attach() callback. Let me know which do you prefer.
Ok, that clarifies a lot of things. Please add the above as a comment in attach(). > > >> > >> Signed-off-by: Tanmay Shah <[email protected]> > >> --- > >> drivers/remoteproc/xlnx_r5_remoteproc.c | 46 +++++++++++++++++++++++++ > >> 1 file changed, 46 insertions(+) > >> > >> diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c > >> b/drivers/remoteproc/xlnx_r5_remoteproc.c > >> index 50a9974f3202..f08806f13800 100644 > >> --- a/drivers/remoteproc/xlnx_r5_remoteproc.c > >> +++ b/drivers/remoteproc/xlnx_r5_remoteproc.c > >> @@ -5,6 +5,7 @@ > >> */ > >> > >> #include <dt-bindings/power/xlnx-zynqmp-power.h> > >> +#include <linux/delay.h> > >> #include <linux/dma-mapping.h> > >> #include <linux/firmware/xlnx-zynqmp.h> > >> #include <linux/kernel.h> > >> @@ -29,6 +30,8 @@ > >> #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 (100 * 1000) > >> + > > > > There are some time constant already defined, please use them. > > Ack. > > > > >> /* > >> * settings for RPU cluster mode which > >> * reflects possible values of xlnx,cluster-mode dt-property > >> @@ -865,6 +868,49 @@ static int zynqmp_r5_get_rsc_table_va(struct > >> zynqmp_r5_core *r5_core) > >> > >> static int zynqmp_r5_attach(struct rproc *rproc) > >> { > >> + struct device *dev = &rproc->dev; > >> + bool wait_for_remote = false; > >> + struct fw_rsc_vdev *rsc; > >> + struct fw_rsc_hdr *hdr; > >> + int i, offset, avail; > >> + > >> + 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; > >> + } > >> + } > >> + > >> + /* kick remote to notify about attach */ > >> + rproc->ops->kick(rproc, 0); > >> + > >> + /* wait for sometime until remote is ready */ > >> + if (wait_for_remote) > >> + usleep_range(100, RPROC_ATTACH_TIMEOUT_US); > > > > Instead of waiting, would it be possible to return -EPROBE_DEFER and let the > > driver core retry mechanic do it's work? > > > > It is not possible to do -EPROBE_DEFER, because attach() callback is not > called only during driver probe. > > It is also called during following command sequence: > > attach() -> detach() -> attach() > > During second attach() callback, we can't do -EPROBE_DEFER, as it's not > driver probe anymore. So I think will have to keep the usleep_range(). Right, but in this case the Cortex-A did not go through an uncontrolled reboot, we know the state of the machine is sound. Do you see a scenario where it would not be the case? > > > Thanks, > > Mathieu > > > >> + > >> +attach_success: > >> dev_dbg(&rproc->dev, "rproc %d attached\n", rproc->index); > >> > >> return 0; > >> > >> base-commit: d4ef36fbd57e610d4c334123ce706a2a71187cae > >> -- > >> 2.34.1 > >> >
