PM / Clocks: Only disable enabled clocks in pm_clk_suspend()
Magnus Damm [Wed, 9 Nov 2011 23:44:10 +0000 (00:44 +0100)]
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>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/base/power/clock_ops.c

index 5f0f85d..428e55e 100644 (file)
@@ -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;
                }
        }