linux-kernel - Re: [PATCH v5] of/promtree: allow DT device matching by fixing 'name' brokenness

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Message-ID: <AANLkTimc37=azh11sYYi6x7gTE=0ybud5tXgxa1TDUMT@mail.gmail.com>
Date:	Thu, 24 Feb 2011 23:06:06 -0700
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Andres Salomon <dilinger@...ued.net>
Cc:	dsd@...top.org, sparclinux@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	davem@...emloft.net
Subject: Re: [PATCH v5] of/promtree: allow DT device matching by fixing 'name' brokenness

On Thu, Feb 24, 2011 at 1:01 PM, Andres Salomon <dilinger@...ued.net> wrote:
> On Thu, 24 Feb 2011 12:42:34 -0700
> Grant Likely <grant.likely@...retlab.ca> wrote:
>> If firmware is buggy, then pkg2path must deal with it.  It is not okay
>> for it to return NULL.  (I know that pkg2path is an OFW command, but
>> in this context it really means the linux wrapper to pkg2path which
>> has the semantics, "give me the unique, full and accurate path for
>> this node").  If OFW pkg2path doesn't work, then the platform code
>> must work around it.  I'm pushing back on this because I do not want
>> to see platform workarounds in the common code.
>
> I'm fine with that, I just don't want to see BUG() happening that
> early.  I think a workaround should be handled in common code.  I agree
> that heroic workarounds for firmware bugs should be handled in
> arch-specific pkg2path hooks, but a simple workaround in common code
> is better than just crashing early in boot (imo).

Alright, you've swayed me a bit.  I've made this change and pushed it
out to devicetree/experimental.  I've also picked up your other patch.
 Let me know if it works for you.

diff --git a/drivers/of/pdt.c b/drivers/of/pdt.c
index 5ab3bd5..4d87b5d 100644
--- a/drivers/of/pdt.c
+++ b/drivers/of/pdt.c
@@ -65,17 +65,25 @@ static inline void irq_trans_init(struct device_node *dp) {

 static char * __init of_pdt_build_full_name(struct device_node *dp)
 {
+       static int failsafe_id = 0; /* for generating unique names on failure */
        char *buf;
        int len;

        if (of_pdt_prom_ops->pkg2path(dp->phandle, NULL, 0, &len))
-               BUG();
+               goto failsafe;

        buf = prom_early_alloc(len + 1);
-       if (!buf)
-               BUG();
        if (of_pdt_prom_ops->pkg2path(dp->phandle, buf, len, &len))
-               BUG();
+               goto failsafe;
+       return buf;
+
+ failsafe:
+       buf = prom_early_alloc(strlen(dp->parent->full_name) +
+                              strlen(dp->name) + 16);
+       sprintf(buf, "%s/%s@...nown%i",
+               of_node_is_root(dp->parent) ? "" : dp->parent->full_name,
+               dp->name, failsafe_id++);
+       pr_err("%s: pkg2path failed; assigning %s\n", __func__, buf);
        return buf;
 }

g.
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