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authorJon Hunter <jon-hunter@ti.com>2012-12-15 12:35:54 +0400
committerPaul Walmsley <paul@pwsan.com>2012-12-15 12:35:54 +0400
commit29f0667f9239c2af48ef51c50b12c0250c65bb2a (patch)
treeb12c5dc4c193479683b1a3d15ce7635d25709d04 /arch/arm/mach-omap2/clockdomain.c
parent8c197ccfb60032859a32381b2e4bd4d2b8fdd338 (diff)
downloadlinux-29f0667f9239c2af48ef51c50b12c0250c65bb2a.tar.xz
ARM: OMAP4: Fix EMU clock domain always on
Commit d043d87 (ARM: OMAP2+: clockdomain: bypass clockdomain handling when disabling unused clks) skips the decrementing of a clock-domains use count if the clocks use count is zero. However, for OMAP4 devices this is causing the EMU clock-domain to be stuck ON as the use count is not getting decremented correctly. The scenario that leads to this problem is described below ... omap_hwmod_setup_all --> _setup --> clkdm_hwmod_enable --> EMU clock domain usecount = 1 --> _enable_clocks --> clk_enable --> trace_clk_div_div usecount = 1 --> clkdm_hwmod_enable --> EMU clock domain usecount = 2 --> _idle --> _disable_clocks --> clk_disable --> trace_clk_div_div usecount = 0 --> clkdm_hwmod_disable --> skips decrement of EMU clock domain usecount because trace_clk_div_div is 0! --> EMU clock domain usecount = 2 --> clkdm_hwmod_disable --> EMU clock domain usecount = 1 Hence, due to the order that a clocks use count is decremented and the clock domain is disabled, it is possible that the clock domain can have a non-zero use count when the actual clock has a use count of 0. Therefore, we should only bypass the clock-domain handling when both the clock-domain and clock in the clock-domain have a use count of 0 and warn when the clock-domain has a zero use count and the clock has a non-zero use count. Signed-off-by: Jon Hunter <jon-hunter@ti.com> [paul@pwsan.com: fixed checkpatch warning] Signed-off-by: Paul Walmsley <paul@pwsan.com>
Diffstat (limited to 'arch/arm/mach-omap2/clockdomain.c')
-rw-r--r--arch/arm/mach-omap2/clockdomain.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c
index 384873580b23..7faf82d4e85c 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -998,7 +998,8 @@ int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk)
spin_lock_irqsave(&clkdm->lock, flags);
/* corner case: disabling unused clocks */
- if (__clk_get_enable_count(clk) == 0)
+ if ((__clk_get_enable_count(clk) == 0) &&
+ (atomic_read(&clkdm->usecount) == 0))
goto ccd_exit;
if (atomic_read(&clkdm->usecount) == 0) {