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Re: [Xen-devel] [PATCH 1/4] arm: parse PSCI node from the host device-tree

On 11/26/2013 12:12 PM, Ian Campbell wrote:
On Mon, 2013-11-25 at 13:02 +0100, Andre Przywara wrote:
+    if ( !dt_property_read_u32(psci, "cpu_on", &psci_host_cpu_on_nr) )
+    {
+        printk("/psci node is missing the \"cpu_on\" property\n");
+        return 4;
+    }

http://www.spinics.net/lists/devicetree/msg05348.html updates the
bindings for PSCI 0.2. I suppose Midway must only support 0.1?

I'd be OK with only supporting 0.1 right now, but it would be useful to
comment either in the code or in the commit message.

(nb: I'm not sure of v4 was the final version of that series)

If I look at http://www.spinics.net/lists/devicetree/msg12293.html
I would keep it as it is - at least until the binding changes. Hopefully there will be a compatibility fallback if cpu_on should change to cpu_on-{32,64}. I will talk to Rob about this and will later send a fix if that is needed. Midway provides an implementation conforming to PSCI 0.2, however the device tree binding is still the one from the current kernel git HEAD.

+    return 0;
  /* Parse the device tree and build the logical map array containing
   * MPIDR values related to logical cpus
   * Code base on Linux arch/arm/kernel/devtree.c
@@ -107,6 +145,11 @@ void __init smp_init_cpus(void)
      bool_t bootcpu_valid = 0;
      int rc;

+    if ( psci_host_init() == 0 )
+    {
+        printk(XENLOG_INFO "Using PSCI for SMP bringup\n");
+    }
      if ( (rc = arch_smp_init()) < 0 )

arch_smp_init is empty on both platforms. arm32 has a comment "TODO:
PSCI" ;-)

I think we can nuke this function while we are here, since it's only
purpose was as a PSCI placehoder.

But arch_smp_init() calls platform_smp_init(), which is not empty for the Exynos, VExpress and OMAP5 (it contains the native SMP bringup for these platforms). So shall I skip the superfluous arch_smp_init() and call platform_smp_init() directly from smpboot.c?
Or keep it as it is and we clean it up later?


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