Re: [PATCH 2/2] memory: of_fixup: adapt to new memory layout

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Feb 11, 2019 at 05:20:13PM +0100, Marco Felsch wrote:
> Since kernel 4.16 the memory nodes got a @<reg> suffix so the fixup
> won't work correctly anymore, because instead of adapting the extisting
> one it creates a new node.
> 
> To be compatible with the old and new layout delete the found memory
> node and create a new one. The new node follows the new @<reg> style.
> 
> The patch also renames the node element to root to make it more clear.
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> ---
>  common/memory.c | 24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
> 
> diff --git a/common/memory.c b/common/memory.c
> index 00fa7c50ff..5402acab8e 100644
> --- a/common/memory.c
> +++ b/common/memory.c
> @@ -224,7 +224,7 @@ int memory_bank_first_find_space(resource_size_t *retstart,
>  
>  #ifdef CONFIG_OFTREE
>  
> -static int of_memory_fixup(struct device_node *node, void *unused)
> +static int of_memory_fixup(struct device_node *root, void *unused)
>  {
>  	struct memory_bank *bank;
>  	int err;
> @@ -232,7 +232,23 @@ static int of_memory_fixup(struct device_node *node, void *unused)
>  	struct device_node *memnode;
>  	u8 tmp[16 * 16]; /* Up to 64-bit address + 64-bit size */
>  
> -	memnode = of_create_node(node, "/memory");
> +	/*
> +	 * Since kernel 4.16 the memory node got a @<reg> suffix. To support
> +	 * the old and the new style delete any found memory node and add it
> +	 * again to be sure that the memory node exists only once. It shouldn't
> +	 * bother older kernels if the memory node has this suffix so adding it
> +	 * following the new style.
> +	 */
> +
> +	memnode = of_find_node_by_name(root, "memory");

We don't need this as the /memory node must have device_type = memory.

> +	if (!memnode)
> +		memnode = of_find_node_by_type(root, "memory");

You shouldn't assume that there's only one /memory node. There can be
multiple.
The /memory node must be a direct child of the root node, so it's
unnecessary to traverse the whole tree using of_find_node_by_type().
Something like for_each_child_of_node_safe(root, tmp, np) fits better.


> +
> +	if (memnode)
> +		of_delete_node(memnode);
> +
> +	/* At this moment we don't know the <reg> val */
> +	memnode = of_create_node(root, "/memory");
>  	if (!memnode)
>  		return -ENOMEM;
>  
> @@ -256,6 +272,10 @@ static int of_memory_fixup(struct device_node *node, void *unused)
>  		return err;
>  	}
>  
> +	/* now adapt the node name */
> +	of_rename_node(memnode, basprintf("memory@%llx",
> +				 of_read_number((u32 *)tmp, addr_cell_len)));

It's also allowed to create one /memory node per memory bank. Maybe
that's more straightforward to implement.

Sascha

-- 
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