linux-kernel - [PATCH] MIPS: Fix early CM probing

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Date:	Mon, 8 Feb 2016 09:46:31 -0800
From:	Paul Burton <paul.burton@...tec.com>
To:	<linux-mips@...ux-mips.org>
CC:	Paul Burton <paul.burton@...tec.com>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Aaro Koskinen <aaro.koskinen@...ia.com>,
	Masahiro Yamada <yamada.masahiro@...ionext.com>,
	Rob Herring <robh@...nel.org>,
	"Alexander Sverdlin" <alexander.sverdlin@...il.com>,
	Peter Hurley <peter@...leysoftware.com>,
	<linux-kernel@...r.kernel.org>,
	Leonid Yegoshin <Leonid.Yegoshin@...tec.com>,
	Jaedon Shin <jaedon.shin@...il.com>,
	"James Hogan" <james.hogan@...tec.com>,
	Jonas Gorski <jogo@...nwrt.org>,
	"Markos Chandras" <markos.chandras@...tec.com>,
	Ralf Baechle <ralf@...ux-mips.org>
Subject: [PATCH] MIPS: Fix early CM probing

Commit c014d164f21d ("MIPS: Add platform callback before initializing
the L2 cache") added a platform_early_l2_init function in order to allow
platforms to probe for the CM before L2 initialisation is performed, so
that CM GCRs are available to mips_sc_probe.

That commit actually fails to do anything useful, since it checks
mips_cm_revision to determine whether it should call mips_cm_probe but
the result of mips_cm_revision will always be 0 until mips_cm_probe has
been called. Thus the "early" mips_cm_probe call never occurs.

Fix this & drop the useless weak platform_early_l2_init function by
simply calling mips_cm_probe from setup_arch. For platforms that don't
select CONFIG_MIPS_CM this will be a no-op, and for those that do it
removes the requirement for them to call mips_cm_probe manually
(although doing so isn't harmful for now).

Signed-off-by: Paul Burton <paul.burton@...tec.com>
---

 arch/mips/kernel/setup.c         |  1 +
 arch/mips/mm/sc-mips.c           | 10 ----------
 arch/mips/mti-malta/malta-init.c |  8 --------
 3 files changed, 1 insertion(+), 18 deletions(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 569a7d5..5fdaf8b 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -782,6 +782,7 @@ static inline void prefill_possible_map(void) {}
 void __init setup_arch(char **cmdline_p)
 {
 	cpu_probe();
+	mips_cm_probe();
 	prom_init();
 
 	setup_early_fdc_console();
diff --git a/arch/mips/mm/sc-mips.c b/arch/mips/mm/sc-mips.c
index 3bd0597..2496475 100644
--- a/arch/mips/mm/sc-mips.c
+++ b/arch/mips/mm/sc-mips.c
@@ -181,10 +181,6 @@ static int __init mips_sc_probe_cm3(void)
 	return 1;
 }
 
-void __weak platform_early_l2_init(void)
-{
-}
-
 static inline int __init mips_sc_probe(void)
 {
 	struct cpuinfo_mips *c = &current_cpu_data;
@@ -194,12 +190,6 @@ static inline int __init mips_sc_probe(void)
 	/* Mark as not present until probe completed */
 	c->scache.flags |= MIPS_CACHE_NOT_PRESENT;
 
-	/*
-	 * Do we need some platform specific probing before
-	 * we configure L2?
-	 */
-	platform_early_l2_init();
-
 	if (mips_cm_revision() >= CM_REV_CM3)
 		return mips_sc_probe_cm3();
 
diff --git a/arch/mips/mti-malta/malta-init.c b/arch/mips/mti-malta/malta-init.c
index 571148c..dc2c521 100644
--- a/arch/mips/mti-malta/malta-init.c
+++ b/arch/mips/mti-malta/malta-init.c
@@ -293,7 +293,6 @@ mips_pci_controller:
 	console_config();
 #endif
 	/* Early detection of CMP support */
-	mips_cm_probe();
 	mips_cpc_probe();
 
 	if (!register_cps_smp_ops())
@@ -304,10 +303,3 @@ mips_pci_controller:
 		return;
 	register_up_smp_ops();
 }
-
-void platform_early_l2_init(void)
-{
-	/* L2 configuration lives in the CM3 */
-	if (mips_cm_revision() >= CM_REV_CM3)
-		mips_cm_probe();
-}
-- 
2.7.0