Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

[Balbir Singh]

On 15/09/16 06:06, Reza Arbab wrote:
> Respect the standard dt "status" property when scanning memory nodes in
> early_init_dt_scan_memory(), so that if the property is present and not
> "okay", 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,
> 
> "disabled"
>   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 

Makes sense, so basically a /memory@  with missing status or status = "okay"
are added, others are skipped. No memblocks corresponding to those nodes
are created either.

Balbir Singh

Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

[Balbir Singh]

On 15/09/16 06:06, Reza Arbab wrote:
> Respect the standard dt "status" property when scanning memory nodes in
> early_init_dt_scan_memory(), so that if the property is present and not
> "okay", 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,
> 
> "disabled"
>   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 

Makes sense, so basically a /memory@  with missing status or status = "okay"
are added, others are skipped. No memblocks corresponding to those nodes
are created either.

Balbir Singh

Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

[Reza Arbab]

On Thu, Sep 15, 2016 at 08:43:08AM -0500, Rob Herring wrote:

On Wed, Sep 14, 2016 at 3:06 PM, Reza Arbab  wrote:

+   status = of_get_flat_dt_prop(node, "status", NULL);
+   add_memory = !status || !strcmp(status, "okay");


Move this into it's own function to mirror the unflattened version
(of_device_is_available). Also, make sure the logic is the same. IIRC,
"ok" is also allowed.


Will do. 


@@ -1057,6 +1062,9 @@ int __init early_init_dt_scan_memory(unsigned long node, 
const char *uname,
pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
(unsigned long long)size);

+   if (!add_memory)
+   continue;


There's no point in checking this in the loop. status applies to the
whole node. Just return up above.


I was trying to preserve that pr_debug output for these nodes, but I'm 
also fine with skipping it.


Thanks for your feedback! I'll spin a v3 of this patchset soon.

--
Reza Arbab

Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

[Reza Arbab]

On Thu, Sep 15, 2016 at 08:43:08AM -0500, Rob Herring wrote:

On Wed, Sep 14, 2016 at 3:06 PM, Reza Arbab  wrote:

+   status = of_get_flat_dt_prop(node, "status", NULL);
+   add_memory = !status || !strcmp(status, "okay");


Move this into it's own function to mirror the unflattened version
(of_device_is_available). Also, make sure the logic is the same. IIRC,
"ok" is also allowed.


Will do. 


@@ -1057,6 +1062,9 @@ int __init early_init_dt_scan_memory(unsigned long node, 
const char *uname,
pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
(unsigned long long)size);

+   if (!add_memory)
+   continue;


There's no point in checking this in the loop. status applies to the
whole node. Just return up above.


I was trying to preserve that pr_debug output for these nodes, but I'm 
also fine with skipping it.


Thanks for your feedback! I'll spin a v3 of this patchset soon.

--
Reza Arbab

Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

[Rob Herring]

On Wed, Sep 14, 2016 at 3:06 PM, Reza Arbab  wrote:
> Respect the standard dt "status" property when scanning memory nodes in
> early_init_dt_scan_memory(), so that if the property is present and not
> "okay", 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,
>
> "disabled"
> 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 
> ---
>  drivers/of/fdt.c | 8 
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 085c638..fc19590 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1022,8 +1022,10 @@ int __init early_init_dt_scan_memory(unsigned long 
> node, const char *uname,
>  int depth, void *data)
>  {
> const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
> +   const char *status;
> const __be32 *reg, *endp;
> int l;
> +   bool add_memory;
>
> /* We are scanning "memory" nodes only */
> if (type == NULL) {
> @@ -1044,6 +1046,9 @@ int __init early_init_dt_scan_memory(unsigned long 
> node, const char *uname,
>
> endp = reg + (l / sizeof(__be32));
>
> +   status = of_get_flat_dt_prop(node, "status", NULL);
> +   add_memory = !status || !strcmp(status, "okay");

Move this into it's own function to mirror the unflattened version
(of_device_is_available). Also, make sure the logic is the same. IIRC,
"ok" is also allowed.

> +
> pr_debug("memory scan node %s, reg size %d,\n", uname, l);
>
> while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
> @@ -1057,6 +1062,9 @@ int __init early_init_dt_scan_memory(unsigned long 
> node, const char *uname,
> pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
> (unsigned long long)size);
>
> +   if (!add_memory)
> +   continue;

There's no point in checking this in the loop. status applies to the
whole node. Just return up above.

Rob

Re: [PATCH v2 1/3] drivers/of: recognize status property of dt memory nodes

[Rob Herring]

On Wed, Sep 14, 2016 at 3:06 PM, Reza Arbab  wrote:
> Respect the standard dt "status" property when scanning memory nodes in
> early_init_dt_scan_memory(), so that if the property is present and not
> "okay", 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,
>
> "disabled"
> 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 
> ---
>  drivers/of/fdt.c | 8 
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 085c638..fc19590 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1022,8 +1022,10 @@ int __init early_init_dt_scan_memory(unsigned long 
> node, const char *uname,
>  int depth, void *data)
>  {
> const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
> +   const char *status;
> const __be32 *reg, *endp;
> int l;
> +   bool add_memory;
>
> /* We are scanning "memory" nodes only */
> if (type == NULL) {
> @@ -1044,6 +1046,9 @@ int __init early_init_dt_scan_memory(unsigned long 
> node, const char *uname,
>
> endp = reg + (l / sizeof(__be32));
>
> +   status = of_get_flat_dt_prop(node, "status", NULL);
> +   add_memory = !status || !strcmp(status, "okay");

Move this into it's own function to mirror the unflattened version
(of_device_is_available). Also, make sure the logic is the same. IIRC,
"ok" is also allowed.

> +
> pr_debug("memory scan node %s, reg size %d,\n", uname, l);
>
> while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
> @@ -1057,6 +1062,9 @@ int __init early_init_dt_scan_memory(unsigned long 
> node, const char *uname,
> pr_debug(" - %llx ,  %llx\n", (unsigned long long)base,
> (unsigned long long)size);
>
> +   if (!add_memory)
> +   continue;

There's no point in checking this in the loop. status applies to the
whole node. Just return up above.

Rob