Re: [PATCH] coresight: STM: Balance enable/disable

[Suzuki K Poulose]

On 13/01/17 16:48, Mathieu Poirier wrote:
> On 10 January 2017 at 04:21, Suzuki K Poulose <suzuki.poulose@xxxxxxx> wrote:
> > The stm is automatically enabled when an application sets the policy
> > via ->link() call back by using coresight_enable(), which keeps the
> > refcount of the current users of the STM. However, the unlink() callback
> > issues stm_disable() directly, which leaves the STM turned off, without
> > the coresight layer knowing about it. This prevents any further uses
> > of the STM hardware as the coresight layer still thinks the STM is
> > turned on and doesn't issue an stm_enable(). Even manually enabling
> > the STM via sysfs can't really enable the hw.
...
> > This patch balances the unlink operation by using the coresight_disable(),
> > keeping the coresight layer in sync with the hardware state.
> >
> > Fixes: commit 237483aa5cf43 ("coresight: stm: adding driver for CoreSight STM component")
> > Cc: Pratik Patel <pratikp@xxxxxxxxxxxxxx>
> > Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > Cc: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx # 4.7+
> > Reported-by: Robert Walker <robert.walker@xxxxxxx>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> >  drivers/hwtracing/coresight/coresight-stm.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> > index 3524452..57b7330 100644
> > --- a/drivers/hwtracing/coresight/coresight-stm.c
> > +++ b/drivers/hwtracing/coresight/coresight-stm.c
> > @@ -356,7 +356,7 @@ static void stm_generic_unlink(struct stm_data *stm_data,
> >         if (!drvdata || !drvdata->csdev)
> >                 return;
> >
> > -       stm_disable(drvdata->csdev, NULL);
> > +       coresight_disable(drvdata->csdev);
> >  }
> >
> >  static phys_addr_t
>
> Applied - thanks,

Mathieu, Greg,

I think this should go into 4.10 (either way, as fix in this cycle or via stable after the release). I think
it would be easier if it goes in as fix during one of these rc cycle.

Please let me know your thoughts.

Suzuki

> Mathieu
>
> > --
> > 2.7.4