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

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Sascha,

On 19-02-12 09:03, Sascha Hauer wrote:
> 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.

Okay, tought about the old devicetrees where the QA wasn't that good. I
will drop this.

> 
> > +	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.

Sure.. damn, checked only a few devicetree's where multiple banks are
mapped to the reg property. I will change this.

> 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.

Okay.

> 
> > +
> > +	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.

Is it wrong to adapt the name later? As specified by DT-Spec [1], the
@<reg> should be set to the first address.

[1]
https://github.com/devicetree-org/devicetree-specification/releases/tag/v0.2,
Chapter 2.2.1

Regards,
Marco

> 
> Sascha
> 
> -- 
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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> 

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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