Re: NXP P50XX/e5500: SMP doesn't work anymore with the latest Git kernel

[Christian Zigotzky]

On 30 October 2018 at 08:27AM, Christian Zigotzky wrote:
On 30 October 2018 at 02:59AM, Benjamin Herrenschmidt wrote:
On Tue, 2018-10-30 at 02:42 +0100, Christian Zigotzky wrote:
OF patch for the latest Git kernel: http://www.xenosoft.de/of_v2.patch
This just seems to revert a whole bunch of stuff, not really the right
way to go. Why is of_get_next_cpu_node() not finding your CPUs ? There
must be something wrong with the device-tree...
Maybe we need a new dtb for QEMU ppce500 and P50XX machines. I don't 
know. For us it is good to have this patch because we can test 
further. (other updates)
With this patch, SMP works again on virtual QEMU ppce500 and P50XX 
machines. If you have another code, then I will test it with QEMU and 
my P5020 board.

Thanks,
Christian
We use the 'cyrus_p5020.dts' file for creating the dtb file for our 
P5020 board. You can find it in the official kernel source code. 
(arch/powerpc/boot/dts/cyrus_p5020.dts)
For the virtual ppce500 machine I don't need to add a dtb file to the 
QEMU command. But maybe there is a solution:

On 30 October 2018 at 3:18PM, Michael Ellerman wrote:
Hi Rob,

Sorry I missed this when you posted it.

Rob Herring <r...@kernel.org> writes:
Iterating thru cpu nodes is a common pattern. Create a common iterator
which can find child nodes either by node name or device_type == cpu.
Using the former will allow for eventually dropping device_type
properties which are deprecated for FDT.
Device trees we see on powerpc generally don't (never?) use "cpu" as the
node name for CPU nodes. And many of those device trees come from
firmware, so we can't update them.

So dropping support for device_type is a non-starter from our POV.

cheers



----------------------------- of_v2.patch -----------------------------

diff -rupN a/drivers/of/base.c b/drivers/of/base.c
--- a/drivers/of/base.c    2018-10-30 02:19:30.827089495 +0100
+++ b/drivers/of/base.c    2018-10-30 02:18:51.666856715 +0100
@@ -395,7 +395,7 @@ struct device_node *of_get_cpu_node(int
   {
       struct device_node *cpun;

-    for_each_of_cpu_node(cpun) {
+    for_each_node_by_type(cpun, "cpu") {
           if (arch_find_n_match_cpu_physical_id(cpun, cpu, thread))
               return cpun;
       }
@@ -750,45 +750,6 @@ struct device_node *of_get_next_availabl
   EXPORT_SYMBOL(of_get_next_available_child);

   /**
- *    of_get_next_cpu_node - Iterate on cpu nodes
- *    @prev:    previous child of the /cpus node, or NULL to get first
- *
- *    Returns a cpu node pointer with refcount incremented, use
of_node_put()
- *    on it when done. Returns NULL when prev is the last child. 
Decrements
- *    the refcount of prev.
- */
-struct device_node *of_get_next_cpu_node(struct device_node *prev)
-{
-    struct device_node *next = NULL;
-    unsigned long flags;
-    struct device_node *node;
-
-    if (!prev)
-        node = of_find_node_by_path("/cpus");
-
-    raw_spin_lock_irqsave(&devtree_lock, flags);
-    if (prev)
-        next = prev->sibling;
-    else if (node) {
-        next = node->child;
-        of_node_put(node);
-    }
-    for (; next; next = next->sibling) {
-        if (!(of_node_name_eq(next, "cpu") ||
-              (next->type && !of_node_cmp(next->type, "cpu"))))
-            continue;
-        if (!__of_device_is_available(next))
-            continue;
-        if (of_node_get(next))
-            break;
-    }
-    of_node_put(prev);
-    raw_spin_unlock_irqrestore(&devtree_lock, flags);
-    return next;
-}
-EXPORT_SYMBOL(of_get_next_cpu_node);
-
-/**
    * of_get_compatible_child - Find compatible child node
    * @parent:    parent node
    * @compatible:    compatible string
diff -rupN a/include/linux/of.h b/include/linux/of.h
--- a/include/linux/of.h    2018-10-30 02:19:32.047096634 +0100
+++ b/include/linux/of.h    2018-10-30 02:18:51.666856715 +0100
@@ -347,7 +347,6 @@ extern const void *of_get_property(const
                   const char *name,
                   int *lenp);
   extern struct device_node *of_get_cpu_node(int cpu, unsigned int 
*thread);
-extern struct device_node *of_get_next_cpu_node(struct device_node 
*prev);

   #define for_each_property_of_node(dn, pp) \
       for (pp = dn->properties; pp != NULL; pp = pp->next)
@@ -757,11 +756,6 @@ static inline struct device_node *of_get
       return NULL;
   }

-static inline struct device_node *of_get_next_cpu_node(struct
device_node *prev)
-{
-    return NULL;
-}
-
   static inline int of_n_addr_cells(struct device_node *np)
   {
       return 0;
@@ -1239,10 +1233,6 @@ static inline int of_property_read_s32(c
       for (child = of_get_next_available_child(parent, NULL); child !=
NULL; \
            child = of_get_next_available_child(parent, child))

-#define for_each_of_cpu_node(cpu) \
-    for (cpu = of_get_next_cpu_node(NULL); cpu != NULL; \
-         cpu = of_get_next_cpu_node(cpu))
-
   #define for_each_node_with_property(dn, prop_name) \
       for (dn = of_find_node_with_property(NULL, prop_name); dn; \
            dn = of_find_node_with_property(dn, prop_name))