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author | Jon Hunter <jon-hunter@ti.com> | 2012-12-15 12:35:54 +0400 |
---|---|---|
committer | Paul Walmsley <paul@pwsan.com> | 2012-12-15 12:35:54 +0400 |
commit | 29f0667f9239c2af48ef51c50b12c0250c65bb2a (patch) | |
tree | b12c5dc4c193479683b1a3d15ce7635d25709d04 /arch/arm/mach-omap2/clockdomain.c | |
parent | 8c197ccfb60032859a32381b2e4bd4d2b8fdd338 (diff) | |
download | linux-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.c | 3 |
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) { |