Re: [PATCH 1/7] OMAP24xx/25xx clock: init osc_ck, sys_ck internal lists early

[Paul Walmsley <paul@pwsan.com>]

On Thu, 23 Apr 2009, Tony Lindgren wrote:

> * Paul Walmsley <paul@pwsan.com> [090423 20:13]:
> > On Thu, 23 Apr 2009, Tony Lindgren wrote:
> > 
> > > * Russell King - ARM Linux <linux@arm.linux.org.uk> [090423 15:26]:
> > > > On Thu, Apr 23, 2009 at 11:00:31AM -0700, Tony Lindgren wrote:
> > > > > * Paul Walmsley <paul@pwsan.com> [090423 01:35]:
> > > > > > Hello Russell,
> > > > > > 
> > > > > > On Thu, 23 Apr 2009, Russell King - ARM Linux wrote:
> > > > > > 
> > > > > > > On Wed, Apr 22, 2009 at 08:01:29PM -0600, Paul Walmsley wrote:
> > > > > > > > The patch also renames clk_init_one() to clk_preinit() to
> > > > > > > > distinguish its function from clk_init() and the individual struct clk
> > > > > > > > init functions.
> > > > > > > 
> > > > > > > That's rather unnecessary.  'clk_init_one' is already unique.  In the
> > > > > > > long run, it's clk_init that needs to go.
> > > > > > 
> > > > > > Even if clk_init() were to disappear, the struct clk .init function 
> > > > > > pointer would still be present.  clk->init() performs a very different 
> > > > > > kind of initialization than clk_init_one().
> > > > > 
> > > > > I'm OK doing the rename in this fix. The original naming can cause
> > > > > confusion while reading the code.
> > > > 
> > > > Well I'm not, and I want to discuss it some more.  And I'm sending Linus
> > > > a pull request tonight, so I'm dropping the OMAP stuff from that.
> > > 
> > > OK. Paul, can you please separate out the rename part into a separate
> > > patch so we only have a minimal fix & then repost it here?
> > > 
> > > That way we'll get the necessary fixes in and you guys can schedule
> > > other changes for next merge window.
> > 
> > The omap-clock-fixes branch has been updated to remove the rename.
> > 
> > Not that this should stop the discussion, but at least this should no 
> > longer prevent these needed fixes from going upstream.
> 
> Care to post the updated patch here too? Temporay git branches are 
> not too readable by most people..

Here you go:

- Paul


From: Paul Walmsley <paul@pwsan.com>
Date: Wed, 22 Apr 2009 19:48:53 -0600
Subject: [PATCH] OMAP2xxx clock: pre-initialize struct clks early

Commit 3f0a820c4c0b4670fb5f164baa5582e23c2ef118 breaks OMAP2xxx boot
during initial propagate_rate() on osc_ck and sys_ck.  Fix by
pre-initializing all struct clks before running any other clock init
code.  Incorporates review comments from Russell King
<rmk+kernel@arm.linux.org.uk>.

Resolves

<1>Unable to handle kernel NULL pointer dereference at virtual address 00000000
<1>pgd = c0004000
<1>[00000000] *pgd=00000000
Internal error: Oops: 5 [#1]
Modules linked in:
CPU: 0    Not tainted  (2.6.29-omap1 #37)
PC is at propagate_rate+0x10/0x60
LR is at omap2_clk_init+0x30/0x218
...

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
---
 arch/arm/mach-omap2/clock24xx.c |    6 +++---
 arch/arm/plat-omap/clock.c      |    7 +++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/clock24xx.c b/arch/arm/mach-omap2/clock24xx.c
index 1e839c5..984fb86 100644
--- a/arch/arm/mach-omap2/clock24xx.c
+++ b/arch/arm/mach-omap2/clock24xx.c
@@ -720,14 +720,14 @@ int __init omap2_clk_init(void)
 
 	clk_init(&omap2_clk_functions);
 
+	for (c = omap24xx_clks; c < omap24xx_clks + ARRAY_SIZE(omap24xx_clks); c++)
+		clk_init_one(c->lk.clk);
+
 	osc_ck.rate = omap2_osc_clk_recalc(&osc_ck);
 	propagate_rate(&osc_ck);
 	sys_ck.rate = omap2_sys_clk_recalc(&sys_ck);
 	propagate_rate(&sys_ck);
 
-	for (c = omap24xx_clks; c < omap24xx_clks + ARRAY_SIZE(omap24xx_clks); c++)
-		clk_init_one(c->lk.clk);
-
 	cpu_mask = 0;
 	if (cpu_is_omap2420())
 		cpu_mask |= CK_242X;
diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c
index 2e06145..29efc27 100644
--- a/arch/arm/plat-omap/clock.c
+++ b/arch/arm/plat-omap/clock.c
@@ -239,6 +239,13 @@ void recalculate_root_clocks(void)
 	}
 }
 
+/**
+ * clk_init_one - initialize any fields in the struct clk before clk init
+ * @clk: struct clk * to initialize
+ *
+ * Initialize any struct clk fields needed before normal clk initialization
+ * can run.  No return value.
+ */
 void clk_init_one(struct clk *clk)
 {
 	INIT_LIST_HEAD(&clk->children);
-- 
1.6.3.rc1.51.gea0b7