[PATCH] PM / Clocks: Only disable enabled clocks in pm_clk_suspend()

[PATCH] PM / Clocks: Only disable enabled clocks in pm_clk_suspend()

[Magnus Damm]

From: Magnus Damm <damm@opensource.se>

Refrain from running clk_disable() on clocks that
have not been enabled. A typical case when this can
happen is during Suspend-to-RAM for devices that have
no driver associated with them. In such case the clock
may be in default ACQUIRED state.

Without this patch the sh7372 Mackerel board crashes
in __clk_disable() during Suspend-to-RAM with:
"Trying to disable clock 0xdeadbeef with 0 usecount"
This happens for the CEU device which is added during
boot. The test case has no CEU driver included in the
kernel configuration. Needed for v3.2-rc1.

Signed-off-by: Magnus Damm <damm@opensource.se>
---

 drivers/base/power/clock_ops.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- 0001/drivers/base/power/clock_ops.c
+++ work/drivers/base/power/clock_ops.c	2011-11-09 19:28:03.000000000 +0900
@@ -229,7 +229,8 @@ int pm_clk_suspend(struct device *dev)
 
 	list_for_each_entry_reverse(ce, &psd->clock_list, node) {
 		if (ce->status < PCE_STATUS_ERROR) {
-			clk_disable(ce->clk);
+			if (ce->status = PCE_STATUS_ENABLED)
+				clk_disable(ce->clk);
 			ce->status = PCE_STATUS_ACQUIRED;
 		}
 	}

Re: [PATCH] PM / Clocks: Only disable enabled clocks in pm_clk_suspend()

[Rafael J. Wysocki]

On Wednesday, November 09, 2011, Magnus Damm wrote:
> From: Magnus Damm <damm@opensource.se>
> 
> Refrain from running clk_disable() on clocks that
> have not been enabled. A typical case when this can
> happen is during Suspend-to-RAM for devices that have
> no driver associated with them. In such case the clock
> may be in default ACQUIRED state.
> 
> Without this patch the sh7372 Mackerel board crashes
> in __clk_disable() during Suspend-to-RAM with:
> "Trying to disable clock 0xdeadbeef with 0 usecount"
> This happens for the CEU device which is added during
> boot. The test case has no CEU driver included in the
> kernel configuration. Needed for v3.2-rc1.
> 
> Signed-off-by: Magnus Damm <damm@opensource.se>

Applied to linux-pm/pm-fixes.

Thanks,
Rafael


> ---
> 
>  drivers/base/power/clock_ops.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> --- 0001/drivers/base/power/clock_ops.c
> +++ work/drivers/base/power/clock_ops.c	2011-11-09 19:28:03.000000000 +0900
> @@ -229,7 +229,8 @@ int pm_clk_suspend(struct device *dev)
>  
>  	list_for_each_entry_reverse(ce, &psd->clock_list, node) {
>  		if (ce->status < PCE_STATUS_ERROR) {
> -			clk_disable(ce->clk);
> +			if (ce->status = PCE_STATUS_ENABLED)
> +				clk_disable(ce->clk);
>  			ce->status = PCE_STATUS_ACQUIRED;
>  		}
>  	}
> --
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