[ARM] OMAP: wait for pwrdm transition after clk_enable()

Enabling clock in a disabled power domain causes the power domain to be
turned on. However, the power transition is not always finished when
clk_enable() returns and this randomly crashes the kernel when an
interrupt happens right after the clk_enable, and the kernel tries to
read the irq status register for that domain.

Why the irq status register is inaccessible, I don't know. Also it
doesn't seem to be related to the module being not powered up, but to
the transition itself.

The same could perhaps happen after clk_disable also, but I have not
witnessed that.

The problem affects at least dss, cam and sgx clocks.

This change waits for the transition to be finished before returning
from omap2_clkdm_clk_enable().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
index e9b4f6c564e4..c9c367c39679 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -568,6 +568,8 @@ int omap2_clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk)
 	else
 		omap2_clkdm_wakeup(clkdm);
 
+	pwrdm_wait_transition(clkdm->pwrdm.ptr);
+
 	return 0;
 }