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Date: Tue, 2 Jan 2024 11:43:27 -0700
From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Tanmay Shah <tanmay.shah@amd.com>
Cc: Bjorn Andersson <andersson@kernel.org>,
	linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Ben Levinsky <ben.levinsky@amd.com>
Subject: Re: [RESEND PATCH v3 1/2] remoteproc: Make rproc_get_by_phandle()
 work for clusters
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On Wed, Dec 20, 2023 at 08:47:19AM -0600, Tanmay Shah wrote:
> 
> On 11/14/23 10:23 AM, Mathieu Poirier wrote:
> > On Tue, 14 Nov 2023 at 08:22, Bjorn Andersson <andersson@kernel.org> wrote:
> > >
> > > On Sat, Oct 14, 2023 at 04:15:47PM -0700, Tanmay Shah wrote:
> > > > From: Mathieu Poirier <mathieu.poirier@linaro.org>
> > > >
> > > > 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.
> > > >
> > > > Reported-by: Ben Levinsky <ben.levinsky@xilinx.com>
> > > > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > > > Tested-by: Ben Levinsky <ben.levinsky@amd.com>
> > > > ---
> > > >  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 695cce218e8c..3a8191803885 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>
> > > > @@ -2111,7 +2112,9 @@ 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);
> > > > @@ -2122,7 +2125,30 @@ 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);
> > >
> > > Both the Ti and Xilinx drivers are using of_platform_populate(), so
> > > their r->dev.parent should have a parent reference to the cluster
> > > device.
> > >
> >
> > So you are proposing to get the cluster's driver using something like
> > r->dev.parent->parent->driver?
> >
> > I will have to verify the parent/child relationship is set up properly
> > through the of_platform_populate().  If it is, following the pointer
> > trail is an equally valid approach and I will respin this set.
> 
> 
> Hi Mathieu,
> 
> I addressed Bjorn's comments and verified on ZynqMP hardware that it's working.
> 
> Let me know if you would like to see v4 with suggested changes.
>

Yes, please send a V4 with the proposed changes.

> 
> Thanks,
> 
> Tanmay
> 
> > > Unless I'm reading the code wrong, I think we should follow that
> > > pointer, rather than taking the detour in the DeviceTree data.
> > >
> > > Regards,
> > > Bjorn
> > >
> > > > +                             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
> > > >