[PATCH v4 2/5] drivers/of: do not add memory for unavailable nodes

From: Reza Arbab
Date: Thu Oct 06 2016 - 14:38:18 EST

Respect the standard dt "status" property when scanning memory nodes in
early_init_dt_scan_memory(), so that if the node is unavailable, no
memory will be added.

The use case at hand is accelerator or device memory, which may be
unusable until post-boot initialization of the memory link. Such a node
can be described in the dt as any other, given its status is "disabled".
Per the device tree specification,

Indicates that the device is not presently operational, but it
might become operational in the future (for example, something
is not plugged in, or switched off).

Once such memory is made operational, it can then be hotplugged.

Signed-off-by: Reza Arbab <arbab@xxxxxxxxxxxxxxxxxx>
drivers/of/fdt.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index b138efb..08e5d94 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1056,6 +1056,9 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
} else if (strcmp(type, "memory") != 0)
return 0;

+ if (!of_flat_dt_device_is_available(node))
+ return 0;
reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
if (reg == NULL)
reg = of_get_flat_dt_prop(node, "reg", &l);