ARM: OMAP5 / DRA7: PM: Set MPUSS-EMIF clock-domain static dependency

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 <santosh.shilimkar@ti.com>
[rnayak@ti.com: DRA7]
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
[nm@ti.com: conflict resolution, dra7]
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>

1 files changed, 33 insertions, 3 deletions

diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
index 0dda6cf8b855..b6f243db200d 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();