On Mon, Jan 13, 2014 at 06:19:23PM -0600, Suman Anna wrote: > The number of hwspinlocks are determined based on the value read > from the IP block's SYSSTATUS register. However, the module may > not be enabled and clocked, and the read may result in a bus error. > > This particular issue is seen rather easily on AM33XX, since the > module wakeup is software controlled, and it is disabled out of > reset. Make sure the module is enabled and clocked before reading > the SYSSTATUS register. > > Signed-off-by: Suman Anna <s-a...@ti.com> > --- > drivers/hwspinlock/omap_hwspinlock.c | 21 ++++++++++++++------- > 1 file changed, 14 insertions(+), 7 deletions(-) > > diff --git a/drivers/hwspinlock/omap_hwspinlock.c > b/drivers/hwspinlock/omap_hwspinlock.c > index 9f56fb2..194886e 100644 > --- a/drivers/hwspinlock/omap_hwspinlock.c > +++ b/drivers/hwspinlock/omap_hwspinlock.c > @@ -101,10 +101,23 @@ static int omap_hwspinlock_probe(struct platform_device > *pdev) > if (!io_base) > return -ENOMEM; > > + /* > + * make sure the module is enabled and clocked before reading > + * the module SYSSTATUS register > + */ > + pm_runtime_enable(&pdev->dev); > + pm_runtime_get_sync(&pdev->dev); > + > /* Determine number of locks */ > i = readl(io_base + SYSSTATUS_OFFSET); > i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET; > > + /* > + * runtime PM will make sure the clock of this module is > + * enabled again iff at least one lock is requested > + */ > + pm_runtime_put(&pdev->dev);
there is a small race here (which was already present previously) where you could return from probe() in a failure case before your PM runtime put request then you would disable pm_runtime while the device was still alive. -- balbi
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