| Message ID | 1354911994-20045-1-git-send-email-jon-hunter@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Jon, On Fri, 7 Dec 2012, Jon Hunter wrote: > 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. Thanks for the fix and the great patch description; queued for v3.8-rc. - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c index 3848735..0b5452d 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) {
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> --- Based and test on current linux-next tree. This has been boot tested on OMAP2420, OMAP3430 and OMAP4430. I have validated suspend is working on OMAP3430. arch/arm/mach-omap2/clockdomain.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)