[02/10] ARM: OMAP5 / DRA7: PM: Set MPUSS-EMIF clock-domain static dependency

Commit Message

Nishanth Menon Aug. 22, 2014, 2:02 p.m. UTC

From: Santosh Shilimkar <[e-mail]>

With EMIF clock-domain put under hardware supervised control, memory
corruption and untraceable crashes are observed on OMAP5. Further
investigation revealed that there is a weakness in the PRCM on this
specific dynamic depedency.

The recommendation is to set MPUSS static dependency towards EMIF
clock-domain to avoid issues. This recommendation holds good for DRA7
family of devices as well.

Signed-off-by: Santosh Shilimkar <[e-mail]>
[[e-mail]: DRA7]
Signed-off-by: Rajendra Nayak <[e-mail]>
[[e-mail]: conflict resolution, dra7]
Signed-off-by: Nishanth Menon <[e-mail]>
---
 arch/arm/mach-omap2/pm44xx.c |   36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

Comments

Kevin Hilman Aug. 27, 2014, 6:44 p.m. UTC | #1

Nishanth Menon <[e-mail]> writes:

> From: Santosh Shilimkar <[e-mail]>
>
> With EMIF clock-domain put under hardware supervised control, memory
> corruption and untraceable crashes are observed on OMAP5. Further
> investigation revealed that there is a weakness in the PRCM on this
> specific dynamic depedency.

hmm, "weakness".  That's a rather polite way of saying bug. :)

Kevin
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Patch

diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
index 0dda6cf..b6f243d 100644
--- a/arch/arm/mach-omap2/pm44xx.c
+++ b/arch/arm/mach-omap2/pm44xx.c
@@ -203,6 +203,32 @@  static inline int omap4_init_static_deps(void)
 }
 
 /**
+ * omap5_dra7_init_static_deps - Init static clkdm dependencies on OMAP5 and
+ *				 DRA7
+ *
+ * The dynamic dependency between MPUSS -> EMIF is broken and has
+ * not worked as expected. The hardware recommendation is to
+ * enable static dependencies for these to avoid system
+ * lock ups or random crashes.
+ */
+static inline int omap5_dra7_init_static_deps(void)
+{
+	struct clockdomain *mpuss_clkdm, *emif_clkdm;
+	int ret;
+
+	mpuss_clkdm = clkdm_lookup("mpu_clkdm");
+	emif_clkdm = clkdm_lookup("emif_clkdm");
+	if (!mpuss_clkdm || !emif_clkdm)
+		return -EINVAL;
+
+	ret = clkdm_add_wkdep(mpuss_clkdm, emif_clkdm);
+	if (ret)
+		pr_err("Failed to add MPUSS -> EMIF wakeup dependency\n");
+
+	return ret;
+}
+
+/**
  * omap4_pm_init_early - Does early initialization necessary for OMAP4+ devices
  *
  * Initializes basic stuff for power management functionality.
@@ -239,10 +265,14 @@  int __init omap4_pm_init(void)
 		goto err2;
 	}
 
-	if (cpu_is_omap44xx()) {
+	if (cpu_is_omap44xx())
 		ret = omap4_init_static_deps();
-		if (ret)
-			goto err2;
+	else if (soc_is_omap54xx() || soc_is_dra7xx())
+		ret = omap5_dra7_init_static_deps();
+
+	if (ret) {
+		pr_err("Failed to initialise static dependencies.\n");
+		goto err2;
 	}
 
 	ret = omap4_mpuss_init();