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    SubjectRe: [PATCH] remoteproc: Make rproc_get_by_phandle() work for clusters
    On Wed, Dec 14, 2022 at 03:16:43PM -0700, Mathieu Poirier wrote:
    > Multi-cluster remoteproc designs typically have the following DT
    > declaration:
    >
    > remoteproc_cluster {
    > compatible = "soc,remoteproc-cluster";
    >
    > core0: core0 {
    > compatible = "soc,remoteproc-core"
    > memory-region;
    > sram;
    > };
    >
    > core1: core1 {
    > compatible = "soc,remoteproc-core"
    > memory-region;
    > sram;
    > }
    > };
    >
    > A driver exists for the cluster rather than the individual cores
    > themselves so that operation mode and HW specific configurations
    > applicable to the cluster can be made.
    >
    > Because the driver exists at the cluster level and not the individual
    > core level, function rproc_get_by_phandle() fails to return the
    > remoteproc associated with the phandled it is called for.
    >
    > This patch enhances rproc_get_by_phandle() by looking for the cluster's
    > driver when the driver for the immediate remoteproc's parent is not
    > found.
    >

    Can you please help me understand why zynqmp_r5_remoteproc_probe()
    invokes devm_of_platform_populate() to create platform_device instances
    for the clusters?

    Why can't the platform_device for the cluster be used as parent for both
    remoteprocs and then the driver deal with the subnodes within the
    driver?

    Regards,
    Bjorn

    > Reported-by: Ben Levinsky <ben.levinsky@xilinx.com>
    > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
    > ---
    > drivers/remoteproc/remoteproc_core.c | 28 +++++++++++++++++++++++++++-
    > 1 file changed, 27 insertions(+), 1 deletion(-)
    >
    > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
    > index 1cd4815a6dd1..91f82886add9 100644
    > --- a/drivers/remoteproc/remoteproc_core.c
    > +++ b/drivers/remoteproc/remoteproc_core.c
    > @@ -33,6 +33,7 @@
    > #include <linux/idr.h>
    > #include <linux/elf.h>
    > #include <linux/crc32.h>
    > +#include <linux/of_platform.h>
    > #include <linux/of_reserved_mem.h>
    > #include <linux/virtio_ids.h>
    > #include <linux/virtio_ring.h>
    > @@ -2110,7 +2111,9 @@ EXPORT_SYMBOL(rproc_detach);
    > #ifdef CONFIG_OF
    > struct rproc *rproc_get_by_phandle(phandle phandle)
    > {
    > + struct platform_device *cluster_pdev;
    > struct rproc *rproc = NULL, *r;
    > + struct device_driver *driver;
    > struct device_node *np;
    >
    > np = of_find_node_by_phandle(phandle);
    > @@ -2121,7 +2124,30 @@ struct rproc *rproc_get_by_phandle(phandle phandle)
    > list_for_each_entry_rcu(r, &rproc_list, node) {
    > if (r->dev.parent && device_match_of_node(r->dev.parent, np)) {
    > /* prevent underlying implementation from being removed */
    > - if (!try_module_get(r->dev.parent->driver->owner)) {
    > +
    > + /*
    > + * If the remoteproc's parent has a driver, the
    > + * remoteproc is not part of a cluster and we can use
    > + * that driver.
    > + */
    > + driver = r->dev.parent->driver;
    > +
    > + /*
    > + * If the remoteproc's parent does not have a driver,
    > + * look for the driver associated with the cluster.
    > + */
    > + if (!driver) {
    > + cluster_pdev = of_find_device_by_node(np->parent);
    > + if (!cluster_pdev) {
    > + dev_err(&r->dev, "can't get parent\n");
    > + break;
    > + }
    > +
    > + driver = cluster_pdev->dev.driver;
    > + put_device(&cluster_pdev->dev);
    > + }
    > +
    > + if (!try_module_get(driver->owner)) {
    > dev_err(&r->dev, "can't get owner\n");
    > break;
    > }
    > --
    > 2.25.1
    >

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