Patchwork of/pdt: allow DT device matching by fixing 'name' brokenness (v2)

login
register
mail settings
Submitter Andres Salomon
Date Feb. 23, 2011, 11:03 p.m.
Message ID <20110223150357.5a40793d@queued.net>
Download mbox | patch
Permalink /patch/84262/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Andres Salomon - Feb. 23, 2011, 11:03 p.m.
Commit e2f2a93b changed dp->name from using the 'name' property to
using package-to-path.  This fixed /proc/device-tree creation by
eliminating conflicts between names (the 'name' property provides
names like 'battery', whereas package-to-path provides names like
'/foo/bar/battery@0', which we stripped to 'battery@0').  However,
it also breaks of_device_id table matching.

The fix that we _really_ wanted was to keep dp->name based upon
the name property ('battery'), but based dp->full_name upon
package-to-path ('battery@0').  This patch does just that.

This also changes OLPC behavior to use the full result from
package-to-path for full_name, rather than stripping the directory
out.  In practice, the strings end up being exactly the same; this
change saves time, code, and memory.

Note that this affects sparc by reverting dp->name back to what
sparc was originally doing (looking at the name property).

v2: combine two patches and revert of_pdt_node_name to original version.

Signed-off-by: Andres Salomon <dilinger@queued.net>
---
 drivers/of/pdt.c |   42 +++++++++++++++---------------------------
 1 files changed, 15 insertions(+), 27 deletions(-)
Grant Likely - Feb. 23, 2011, 11:28 p.m.
On Wed, Feb 23, 2011 at 03:03:57PM -0800, Andres Salomon wrote:
> 
> Commit e2f2a93b changed dp->name from using the 'name' property to
> using package-to-path.  This fixed /proc/device-tree creation by
> eliminating conflicts between names (the 'name' property provides
> names like 'battery', whereas package-to-path provides names like
> '/foo/bar/battery@0', which we stripped to 'battery@0').  However,
> it also breaks of_device_id table matching.
> 
> The fix that we _really_ wanted was to keep dp->name based upon
> the name property ('battery'), but based dp->full_name upon
> package-to-path ('battery@0').  This patch does just that.
> 
> This also changes OLPC behavior to use the full result from
> package-to-path for full_name, rather than stripping the directory
> out.  In practice, the strings end up being exactly the same; this
> change saves time, code, and memory.
> 
> Note that this affects sparc by reverting dp->name back to what
> sparc was originally doing (looking at the name property).
> 
> v2: combine two patches and revert of_pdt_node_name to original version.
> 
> Signed-off-by: Andres Salomon <dilinger@queued.net>

Hi Andres, comments below.

g.

> ---
>  drivers/of/pdt.c |   42 +++++++++++++++---------------------------
>  1 files changed, 15 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> index 28295d0..a7aa85e 100644
> --- a/drivers/of/pdt.c
> +++ b/drivers/of/pdt.c
> @@ -134,7 +134,7 @@ static char * __init of_pdt_get_one_property(phandle node, const char *name)
>  
>  static char * __init of_pdt_try_pkg2path(phandle node)
>  {
> -	char *res, *buf = NULL;
> +	char *buf = NULL;
>  	int len;
>  
>  	if (!of_pdt_prom_ops->pkg2path)
> @@ -147,29 +147,6 @@ static char * __init of_pdt_try_pkg2path(phandle node)
>  		pr_err("%s: package-to-path failed\n", __func__);
>  		return NULL;
>  	}
> -
> -	res = strrchr(buf, '/');
> -	if (!res) {
> -		pr_err("%s: couldn't find / in %s\n", __func__, buf);
> -		return NULL;
> -	}
> -	return res+1;
> -}
> -
> -/*
> - * When fetching the node's name, first try using package-to-path; if
> - * that fails (either because the arch hasn't supplied a PROM callback,
> - * or some other random failure), fall back to just looking at the node's
> - * 'name' property.
> - */
> -static char * __init of_pdt_build_name(phandle node)
> -{
> -	char *buf;
> -
> -	buf = of_pdt_try_pkg2path(node);
> -	if (!buf)
> -		buf = of_pdt_get_one_property(node, "name");
> -
>  	return buf;
>  }
>  

It seems to me that of_pdt_build_full_name will still be missing the
'@<addr>' component on non-sparc non-olpc builds because it uses the
broken of_pdt_node_name().  That needs to be fixed too, even if there
are no current users (or removed).

> @@ -187,7 +164,7 @@ static struct device_node * __init of_pdt_create_node(phandle node,
>  
>  	kref_init(&dp->kref);
>  
> -	dp->name = of_pdt_build_name(node);
> +	dp->name = of_pdt_get_one_property(node, "name");
>  	dp->type = of_pdt_get_one_property(node, "device_type");
>  	dp->phandle = node;
>  
> @@ -198,11 +175,22 @@ static struct device_node * __init of_pdt_create_node(phandle node,
>  	return dp;
>  }
>  
> -static char * __init of_pdt_build_full_name(struct device_node *dp)
> +static char * __init of_pdt_build_full_name(struct device_node *dp,
> +		phandle node)

Is dp->phandle not suitable here?

>  {
>  	int len, ourlen, plen;
>  	char *n;
>  
> +	/*
> +	 * When fetching the full name we want the name we see with
> +	 * package-to-path (ie, '/foo/bar/battery@0') rather than what
> +	 * we see with the name property (ie, 'battery').
> +	 */
> +	n = of_pdt_try_pkg2path(node);
> +	if (n)
> +		return n;
> +
> +	/* Older method for determining full name */
>  	plen = strlen(dp->parent->full_name);
>  	ourlen = strlen(of_pdt_node_name(dp));
>  	len = ourlen + plen + 2;
> @@ -243,7 +231,7 @@ static struct device_node * __init of_pdt_build_tree(struct device_node *parent,
>  #if defined(CONFIG_SPARC)
>  		dp->path_component_name = build_path_component(dp);
>  #endif

I still think it would be useful to remove the #if
defined(CONFIG_SPARC) from path_component_name, and it might be the
best way to solve my comment about broken of_pdt_node_name above.

> -		dp->full_name = of_pdt_build_full_name(dp);
> +		dp->full_name = of_pdt_build_full_name(dp, node);
>  
>  		dp->child = of_pdt_build_tree(dp,
>  				of_pdt_prom_ops->getchild(node), nextp);
> -- 
> 1.7.2.3
> 
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Andres Salomon - Feb. 24, 2011, 12:16 a.m.
On Wed, 23 Feb 2011 16:28:15 -0700
Grant Likely <grant.likely@secretlab.ca> wrote:

> On Wed, Feb 23, 2011 at 03:03:57PM -0800, Andres Salomon wrote:
> > 
> > Commit e2f2a93b changed dp->name from using the 'name' property to
> > using package-to-path.  This fixed /proc/device-tree creation by
> > eliminating conflicts between names (the 'name' property provides
> > names like 'battery', whereas package-to-path provides names like
> > '/foo/bar/battery@0', which we stripped to 'battery@0').  However,
> > it also breaks of_device_id table matching.
> > 
> > The fix that we _really_ wanted was to keep dp->name based upon
> > the name property ('battery'), but based dp->full_name upon
> > package-to-path ('battery@0').  This patch does just that.
> > 
> > This also changes OLPC behavior to use the full result from
> > package-to-path for full_name, rather than stripping the directory
> > out.  In practice, the strings end up being exactly the same; this
> > change saves time, code, and memory.
> > 
> > Note that this affects sparc by reverting dp->name back to what
> > sparc was originally doing (looking at the name property).
> > 
> > v2: combine two patches and revert of_pdt_node_name to original
> > version.
> > 
> > Signed-off-by: Andres Salomon <dilinger@queued.net>
> 
> Hi Andres, comments below.
> 
> g.
> 
> > ---
> >  drivers/of/pdt.c |   42 +++++++++++++++---------------------------
> >  1 files changed, 15 insertions(+), 27 deletions(-)
> > 
> > diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> > index 28295d0..a7aa85e 100644
> > --- a/drivers/of/pdt.c
> > +++ b/drivers/of/pdt.c
> > @@ -134,7 +134,7 @@ static char * __init
> > of_pdt_get_one_property(phandle node, const char *name) 
> >  static char * __init of_pdt_try_pkg2path(phandle node)
> >  {
> > -	char *res, *buf = NULL;
> > +	char *buf = NULL;
> >  	int len;
> >  
> >  	if (!of_pdt_prom_ops->pkg2path)
> > @@ -147,29 +147,6 @@ static char * __init
> > of_pdt_try_pkg2path(phandle node) pr_err("%s: package-to-path
> > failed\n", __func__); return NULL;
> >  	}
> > -
> > -	res = strrchr(buf, '/');
> > -	if (!res) {
> > -		pr_err("%s: couldn't find / in %s\n", __func__,
> > buf);
> > -		return NULL;
> > -	}
> > -	return res+1;
> > -}
> > -
> > -/*
> > - * When fetching the node's name, first try using package-to-path;
> > if
> > - * that fails (either because the arch hasn't supplied a PROM
> > callback,
> > - * or some other random failure), fall back to just looking at the
> > node's
> > - * 'name' property.
> > - */
> > -static char * __init of_pdt_build_name(phandle node)
> > -{
> > -	char *buf;
> > -
> > -	buf = of_pdt_try_pkg2path(node);
> > -	if (!buf)
> > -		buf = of_pdt_get_one_property(node, "name");
> > -
> >  	return buf;
> >  }
> >  
> 
> It seems to me that of_pdt_build_full_name will still be missing the
> '@<addr>' component on non-sparc non-olpc builds because it uses the
> broken of_pdt_node_name().  That needs to be fixed too, even if there
> are no current users (or removed).


The intent if for them to use the pkg2path hook.  If
they can't use that, they'll need an architecture-specific way to
figure out the @<addr> component.  It may even be possible for sparc
to use package-to-path; but either way, if an architecture doesn't
have package-to-path (OLPC and powerpc have it; I don't know about
sparc), and can't fake it, it'll need to do something special.

If the pkg2path hook isn't set and we're not sparc, we fall back to
dp->name.  That sucks, but I don't know of a better way to do things.



> 
> > @@ -187,7 +164,7 @@ static struct device_node * __init
> > of_pdt_create_node(phandle node, 
> >  	kref_init(&dp->kref);
> >  
> > -	dp->name = of_pdt_build_name(node);
> > +	dp->name = of_pdt_get_one_property(node, "name");
> >  	dp->type = of_pdt_get_one_property(node, "device_type");
> >  	dp->phandle = node;
> >  
> > @@ -198,11 +175,22 @@ static struct device_node * __init
> > of_pdt_create_node(phandle node, return dp;
> >  }
> >  
> > -static char * __init of_pdt_build_full_name(struct device_node *dp)
> > +static char * __init of_pdt_build_full_name(struct device_node *dp,
> > +		phandle node)
> 
> Is dp->phandle not suitable here?
> 
> >  {
> >  	int len, ourlen, plen;
> >  	char *n;
> >  
> > +	/*
> > +	 * When fetching the full name we want the name we see with
> > +	 * package-to-path (ie, '/foo/bar/battery@0') rather than
> > what
> > +	 * we see with the name property (ie, 'battery').
> > +	 */
> > +	n = of_pdt_try_pkg2path(node);
> > +	if (n)
> > +		return n;
> > +
> > +	/* Older method for determining full name */
> >  	plen = strlen(dp->parent->full_name);
> >  	ourlen = strlen(of_pdt_node_name(dp));
> >  	len = ourlen + plen + 2;
> > @@ -243,7 +231,7 @@ static struct device_node * __init
> > of_pdt_build_tree(struct device_node *parent, #if
> > defined(CONFIG_SPARC) dp->path_component_name =
> > build_path_component(dp); #endif
> 
> I still think it would be useful to remove the #if
> defined(CONFIG_SPARC) from path_component_name, and it might be the
> best way to solve my comment about broken of_pdt_node_name above.
> 

path_component_name is filled in by build_path_component() in
sparc-land.  It's very sparc-specific, and having path_component_name
around doesn't help us on other architectures if we don't know how to
fill it in.


> > -		dp->full_name = of_pdt_build_full_name(dp);
> > +		dp->full_name = of_pdt_build_full_name(dp, node);
> >  
> >  		dp->child = of_pdt_build_tree(dp,
> >  				of_pdt_prom_ops->getchild(node),
> > nextp); -- 
> > 1.7.2.3
> > 
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Grant Likely - Feb. 24, 2011, 4:06 a.m.
On Wed, Feb 23, 2011 at 04:16:30PM -0800, Andres Salomon wrote:
> On Wed, 23 Feb 2011 16:28:15 -0700
> Grant Likely <grant.likely@secretlab.ca> wrote:
> 
> > On Wed, Feb 23, 2011 at 03:03:57PM -0800, Andres Salomon wrote:
> > > 
> > > Commit e2f2a93b changed dp->name from using the 'name' property to
> > > using package-to-path.  This fixed /proc/device-tree creation by
> > > eliminating conflicts between names (the 'name' property provides
> > > names like 'battery', whereas package-to-path provides names like
> > > '/foo/bar/battery@0', which we stripped to 'battery@0').  However,
> > > it also breaks of_device_id table matching.
> > > 
> > > The fix that we _really_ wanted was to keep dp->name based upon
> > > the name property ('battery'), but based dp->full_name upon
> > > package-to-path ('battery@0').  This patch does just that.
> > > 
> > > This also changes OLPC behavior to use the full result from
> > > package-to-path for full_name, rather than stripping the directory
> > > out.  In practice, the strings end up being exactly the same; this
> > > change saves time, code, and memory.
> > > 
> > > Note that this affects sparc by reverting dp->name back to what
> > > sparc was originally doing (looking at the name property).
> > > 
> > > v2: combine two patches and revert of_pdt_node_name to original
> > > version.
> > > 
> > > Signed-off-by: Andres Salomon <dilinger@queued.net>
> > 
> > Hi Andres, comments below.
> > 
> > g.
> > 
> > > ---
> > >  drivers/of/pdt.c |   42 +++++++++++++++---------------------------
> > >  1 files changed, 15 insertions(+), 27 deletions(-)
> > > 
> > > diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> > > index 28295d0..a7aa85e 100644
> > > --- a/drivers/of/pdt.c
> > > +++ b/drivers/of/pdt.c
> > > @@ -134,7 +134,7 @@ static char * __init
> > > of_pdt_get_one_property(phandle node, const char *name) 
> > >  static char * __init of_pdt_try_pkg2path(phandle node)
> > >  {
> > > -	char *res, *buf = NULL;
> > > +	char *buf = NULL;
> > >  	int len;
> > >  
> > >  	if (!of_pdt_prom_ops->pkg2path)
> > > @@ -147,29 +147,6 @@ static char * __init
> > > of_pdt_try_pkg2path(phandle node) pr_err("%s: package-to-path
> > > failed\n", __func__); return NULL;
> > >  	}
> > > -
> > > -	res = strrchr(buf, '/');
> > > -	if (!res) {
> > > -		pr_err("%s: couldn't find / in %s\n", __func__,
> > > buf);
> > > -		return NULL;
> > > -	}
> > > -	return res+1;
> > > -}
> > > -
> > > -/*
> > > - * When fetching the node's name, first try using package-to-path;
> > > if
> > > - * that fails (either because the arch hasn't supplied a PROM
> > > callback,
> > > - * or some other random failure), fall back to just looking at the
> > > node's
> > > - * 'name' property.
> > > - */
> > > -static char * __init of_pdt_build_name(phandle node)
> > > -{
> > > -	char *buf;
> > > -
> > > -	buf = of_pdt_try_pkg2path(node);
> > > -	if (!buf)
> > > -		buf = of_pdt_get_one_property(node, "name");
> > > -
> > >  	return buf;
> > >  }
> > >  
> > 
> > It seems to me that of_pdt_build_full_name will still be missing the
> > '@<addr>' component on non-sparc non-olpc builds because it uses the
> > broken of_pdt_node_name().  That needs to be fixed too, even if there
> > are no current users (or removed).
> 
> 
> The intent if for them to use the pkg2path hook.  If
> they can't use that, they'll need an architecture-specific way to
> figure out the @<addr> component.  It may even be possible for sparc
> to use package-to-path; but either way, if an architecture doesn't
> have package-to-path (OLPC and powerpc have it; I don't know about
> sparc), and can't fake it, it'll need to do something special.
> 
> If the pkg2path hook isn't set and we're not sparc, we fall back to
> dp->name.  That sucks, but I don't know of a better way to do things.

More that sucks, it is just plain *wrong*.  :-)

so, to sum up, of_pdt_build_tree goes through the following process:

1) dp = of_pdt_create_node
  - dp->name = of_pdt_get_one_property(node, "name"); /* name w/o addr */

2) (SPARC) dp->path_component_name = build_path_component(dp);
  - format <node name>@<address>
  - uses dp->name value
  - not on OLPC

3) dp->full_name = of_pdt_build_full_name(dp)
  - (SPARC) use dp->path_component_name
  - (OLPC) depend on value from of_pdt_try_pkg2path(node);
  - (others) fake it with an incorrect value?

Am I correct?

Faking it is clearly not acceptable.  The solution is to *force* all
platforms to implement a method for obtaining the full path.  That
means BUG() or WARN() if pkg2path is not populated, or if it returns
NULL.  It also means no mucking about with of_pdt_try_pkg2path().
Call ops->pkg2path directly and complain loudly when it does not work.

I see two choices:
1) implement ops->pkg2path for SPARC, but back it with
   build_path_component() instead of a call to OF
2) #ifdef of_pdt_build_full_name() to use the current behaviour for
   SPARC, but call pkg2path for everyone else.

Actually, I'd like to see build_path_component() refactored to return
the full_name instead.  It is trivial to get the path component from
the full name at any time, but it is not trivial to go the other
direction.... but that is probably more surgery than should be done in
this immediate bug-fix.  I'm assuming a fix is necessary before 2.6.38
is finalized?

g.
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Andres Salomon - Feb. 24, 2011, 4:36 a.m.
On Wed, 23 Feb 2011 21:06:38 -0700
Grant Likely <grant.likely@secretlab.ca> wrote:

> On Wed, Feb 23, 2011 at 04:16:30PM -0800, Andres Salomon wrote:
> > On Wed, 23 Feb 2011 16:28:15 -0700
> > Grant Likely <grant.likely@secretlab.ca> wrote:
> > 
> > > On Wed, Feb 23, 2011 at 03:03:57PM -0800, Andres Salomon wrote:
> > > > 
> > > > Commit e2f2a93b changed dp->name from using the 'name' property
> > > > to using package-to-path.  This fixed /proc/device-tree
> > > > creation by eliminating conflicts between names (the 'name'
> > > > property provides names like 'battery', whereas package-to-path
> > > > provides names like '/foo/bar/battery@0', which we stripped to
> > > > 'battery@0').  However, it also breaks of_device_id table
> > > > matching.
> > > > 
> > > > The fix that we _really_ wanted was to keep dp->name based upon
> > > > the name property ('battery'), but based dp->full_name upon
> > > > package-to-path ('battery@0').  This patch does just that.
> > > > 
> > > > This also changes OLPC behavior to use the full result from
> > > > package-to-path for full_name, rather than stripping the
> > > > directory out.  In practice, the strings end up being exactly
> > > > the same; this change saves time, code, and memory.
> > > > 
> > > > Note that this affects sparc by reverting dp->name back to what
> > > > sparc was originally doing (looking at the name property).
> > > > 
> > > > v2: combine two patches and revert of_pdt_node_name to original
> > > > version.
> > > > 
> > > > Signed-off-by: Andres Salomon <dilinger@queued.net>
> > > 
> > > Hi Andres, comments below.
> > > 
> > > g.
> > > 
> > > > ---
> > > >  drivers/of/pdt.c |   42
> > > > +++++++++++++++--------------------------- 1 files changed, 15
> > > > insertions(+), 27 deletions(-)
> > > > 
> > > > diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
> > > > index 28295d0..a7aa85e 100644
> > > > --- a/drivers/of/pdt.c
> > > > +++ b/drivers/of/pdt.c
> > > > @@ -134,7 +134,7 @@ static char * __init
> > > > of_pdt_get_one_property(phandle node, const char *name) 
> > > >  static char * __init of_pdt_try_pkg2path(phandle node)
> > > >  {
> > > > -	char *res, *buf = NULL;
> > > > +	char *buf = NULL;
> > > >  	int len;
> > > >  
> > > >  	if (!of_pdt_prom_ops->pkg2path)
> > > > @@ -147,29 +147,6 @@ static char * __init
> > > > of_pdt_try_pkg2path(phandle node) pr_err("%s: package-to-path
> > > > failed\n", __func__); return NULL;
> > > >  	}
> > > > -
> > > > -	res = strrchr(buf, '/');
> > > > -	if (!res) {
> > > > -		pr_err("%s: couldn't find / in %s\n", __func__,
> > > > buf);
> > > > -		return NULL;
> > > > -	}
> > > > -	return res+1;
> > > > -}
> > > > -
> > > > -/*
> > > > - * When fetching the node's name, first try using
> > > > package-to-path; if
> > > > - * that fails (either because the arch hasn't supplied a PROM
> > > > callback,
> > > > - * or some other random failure), fall back to just looking at
> > > > the node's
> > > > - * 'name' property.
> > > > - */
> > > > -static char * __init of_pdt_build_name(phandle node)
> > > > -{
> > > > -	char *buf;
> > > > -
> > > > -	buf = of_pdt_try_pkg2path(node);
> > > > -	if (!buf)
> > > > -		buf = of_pdt_get_one_property(node, "name");
> > > > -
> > > >  	return buf;
> > > >  }
> > > >  
> > > 
> > > It seems to me that of_pdt_build_full_name will still be missing
> > > the '@<addr>' component on non-sparc non-olpc builds because it
> > > uses the broken of_pdt_node_name().  That needs to be fixed too,
> > > even if there are no current users (or removed).
> > 
> > 
> > The intent if for them to use the pkg2path hook.  If
> > they can't use that, they'll need an architecture-specific way to
> > figure out the @<addr> component.  It may even be possible for sparc
> > to use package-to-path; but either way, if an architecture doesn't
> > have package-to-path (OLPC and powerpc have it; I don't know about
> > sparc), and can't fake it, it'll need to do something special.
> > 
> > If the pkg2path hook isn't set and we're not sparc, we fall back to
> > dp->name.  That sucks, but I don't know of a better way to do
> > things.
> 
> More that sucks, it is just plain *wrong*.  :-)
> 
> so, to sum up, of_pdt_build_tree goes through the following process:
> 
> 1) dp = of_pdt_create_node
>   - dp->name = of_pdt_get_one_property(node, "name"); /* name w/o
> addr */
> 
> 2) (SPARC) dp->path_component_name = build_path_component(dp);
>   - format <node name>@<address>
>   - uses dp->name value
>   - not on OLPC

Also:
  - returns only the node name, not the full path
  - implemented differently depending upon bus type (see
    pci_path_component/sbus_path_component/ebus_path_component/ambapp_path_component)
  - sparc32 implemented differently versus sparc64

> 
> 3) dp->full_name = of_pdt_build_full_name(dp)
>   - (SPARC) use dp->path_component_name
>   - (OLPC) depend on value from of_pdt_try_pkg2path(node);
>   - (others) fake it with an incorrect value?
> 
> Am I correct?

No.

(others) use of_pdt_try_pkg2path

The reason why we fall back to dp->name is because I don't know what
other architectures out there might not have package-to-path.  I'm
perfectly fine with falling back to a WARN or BUG.

> 
> Faking it is clearly not acceptable.  The solution is to *force* all
> platforms to implement a method for obtaining the full path.  That
> means BUG() or WARN() if pkg2path is not populated, or if it returns
> NULL.  It also means no mucking about with of_pdt_try_pkg2path().
> Call ops->pkg2path directly and complain loudly when it does not work.
> 
> I see two choices:
> 1) implement ops->pkg2path for SPARC, but back it with
>    build_path_component() instead of a call to OF
> 2) #ifdef of_pdt_build_full_name() to use the current behaviour for
>    SPARC, but call pkg2path for everyone else.

Either of these are fine, but I don't think they should be within the
scope of the proposed patch.  I'd like to hear from Davem about whether
#1 is doable.  Also note that ops are different for sparc32 and sparc64.



> 
> Actually, I'd like to see build_path_component() refactored to return
> the full_name instead.  It is trivial to get the path component from


Again, this is Davem-land; I don't have a sparc machine to test any of
this with.  The proposed patch is a bug fix that I'd like to see go in;
I'm perfectly happy to refactor the APIs after that.


> the full name at any time, but it is not trivial to go the other
> direction.... but that is probably more surgery than should be done in
> this immediate bug-fix.  I'm assuming a fix is necessary before 2.6.38
> is finalized?

Well, a fix only affects Daniel's work.  It does, however, fix a bug
in sparc code.  I don't know if that breaks anything in practice.
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Grant Likely - Feb. 24, 2011, 5:38 a.m.
On Wed, Feb 23, 2011 at 08:36:49PM -0800, Andres Salomon wrote:
> On Wed, 23 Feb 2011 21:06:38 -0700
> Grant Likely <grant.likely@secretlab.ca> wrote:
> 
> > > If the pkg2path hook isn't set and we're not sparc, we fall back to
> > > dp->name.  That sucks, but I don't know of a better way to do
> > > things.
> > 
> > More that sucks, it is just plain *wrong*.  :-)
> > 
> > so, to sum up, of_pdt_build_tree goes through the following process:
> > 
> > 1) dp = of_pdt_create_node
> >   - dp->name = of_pdt_get_one_property(node, "name"); /* name w/o
> > addr */
> > 
> > 2) (SPARC) dp->path_component_name = build_path_component(dp);
> >   - format <node name>@<address>
> >   - uses dp->name value
> >   - not on OLPC
> 
> Also:
>   - returns only the node name, not the full path
>   - implemented differently depending upon bus type (see
>     pci_path_component/sbus_path_component/ebus_path_component/ambapp_path_component)
>   - sparc32 implemented differently versus sparc64
> 
> > 
> > 3) dp->full_name = of_pdt_build_full_name(dp)
> >   - (SPARC) use dp->path_component_name
> >   - (OLPC) depend on value from of_pdt_try_pkg2path(node);
> >   - (others) fake it with an incorrect value?
> > 
> > Am I correct?
> 
> No.
> 
> (others) use of_pdt_try_pkg2path

Regardless, in all cases the semantics are absolutely clear; all
platforms *must* have a reliable way of obtaining the full path and
the path_component_name.  It it doesn't then it is fundamentally
broken.

> The reason why we fall back to dp->name is because I don't know what
> other architectures out there might not have package-to-path.  I'm
> perfectly fine with falling back to a WARN or BUG.

Respin to fallback on WARN() and bail out.  I'd be okay with merging a
patch that does that.  Falling back to dp->name is absolutely incorrect.

I agree that API refinements can be deferred to 2.6.39.

g.

--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
index 28295d0..a7aa85e 100644
--- a/drivers/of/pdt.c
+++ b/drivers/of/pdt.c
@@ -134,7 +134,7 @@  static char * __init of_pdt_get_one_property(phandle node, const char *name)
 
 static char * __init of_pdt_try_pkg2path(phandle node)
 {
-	char *res, *buf = NULL;
+	char *buf = NULL;
 	int len;
 
 	if (!of_pdt_prom_ops->pkg2path)
@@ -147,29 +147,6 @@  static char * __init of_pdt_try_pkg2path(phandle node)
 		pr_err("%s: package-to-path failed\n", __func__);
 		return NULL;
 	}
-
-	res = strrchr(buf, '/');
-	if (!res) {
-		pr_err("%s: couldn't find / in %s\n", __func__, buf);
-		return NULL;
-	}
-	return res+1;
-}
-
-/*
- * When fetching the node's name, first try using package-to-path; if
- * that fails (either because the arch hasn't supplied a PROM callback,
- * or some other random failure), fall back to just looking at the node's
- * 'name' property.
- */
-static char * __init of_pdt_build_name(phandle node)
-{
-	char *buf;
-
-	buf = of_pdt_try_pkg2path(node);
-	if (!buf)
-		buf = of_pdt_get_one_property(node, "name");
-
 	return buf;
 }
 
@@ -187,7 +164,7 @@  static struct device_node * __init of_pdt_create_node(phandle node,
 
 	kref_init(&dp->kref);
 
-	dp->name = of_pdt_build_name(node);
+	dp->name = of_pdt_get_one_property(node, "name");
 	dp->type = of_pdt_get_one_property(node, "device_type");
 	dp->phandle = node;
 
@@ -198,11 +175,22 @@  static struct device_node * __init of_pdt_create_node(phandle node,
 	return dp;
 }
 
-static char * __init of_pdt_build_full_name(struct device_node *dp)
+static char * __init of_pdt_build_full_name(struct device_node *dp,
+		phandle node)
 {
 	int len, ourlen, plen;
 	char *n;
 
+	/*
+	 * When fetching the full name we want the name we see with
+	 * package-to-path (ie, '/foo/bar/battery@0') rather than what
+	 * we see with the name property (ie, 'battery').
+	 */
+	n = of_pdt_try_pkg2path(node);
+	if (n)
+		return n;
+
+	/* Older method for determining full name */
 	plen = strlen(dp->parent->full_name);
 	ourlen = strlen(of_pdt_node_name(dp));
 	len = ourlen + plen + 2;
@@ -243,7 +231,7 @@  static struct device_node * __init of_pdt_build_tree(struct device_node *parent,
 #if defined(CONFIG_SPARC)
 		dp->path_component_name = build_path_component(dp);
 #endif
-		dp->full_name = of_pdt_build_full_name(dp);
+		dp->full_name = of_pdt_build_full_name(dp, node);
 
 		dp->child = of_pdt_build_tree(dp,
 				of_pdt_prom_ops->getchild(node), nextp);