[alsa-devel] [PATCH 3/4] soundwire: bus: check if pm runtime is enabled before calling

[Vinod Koul]

On 28-03-19, 14:37, Srinivas Kandagatla wrote:
> 
> 
> On 28/03/2019 13:55, Pierre-Louis Bossart wrote:
> > On 3/28/19 9:41 AM, Srinivas Kandagatla wrote:
> > > Check the device has pm runtime enabled before returning error.
> > > 
> > > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
> > > ---
> > >   drivers/soundwire/bus.c | 16 ++++++++++------
> > >   1 file changed, 10 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> > > index 1cbfedfc20ef..101562a6fb0d 100644
> > > --- a/drivers/soundwire/bus.c
> > > +++ b/drivers/soundwire/bus.c
> > > @@ -327,9 +327,11 @@ int sdw_nread(struct sdw_slave *slave, u32
> > > addr, size_t count, u8 *val)
> > >       if (ret < 0)
> > >           return ret;
> > > -    ret = pm_runtime_get_sync(slave->bus->dev);
> > > -    if (ret < 0)
> > > -        return ret;
> > > +    if (pm_runtime_enabled(slave->bus->dev)) {
> > > +        ret = pm_runtime_get_sync(slave->bus->dev);
> > 
> > Is this an recommended/accepted sequence in kernel circles? I did a
> > quick git grep and don't see anyone using this sort of tests.
> 
> There are lots of users in kernel with such sequences, ex:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iommu/arm-smmu.c?h=v5.1-rc2#n279

Sorry not a fan of this :) I think PM core should do this :D

I guess you are trying to solve the case where PM can be disabled for a
device and pm_runtime_get_sync() returns error right?

That would be quite a common sequence in most frameworks..

Thanks


> 
> > 
> > 
> > > +        if (ret < 0)
> > > +            return ret;
> > > +    }
> > >       ret = sdw_transfer(slave->bus, &msg);
> > >       pm_runtime_put(slave->bus->dev);
> > 
> > and the weird thing is that you don't test for the put() case?
> > 
> > > @@ -355,9 +357,11 @@ int sdw_nwrite(struct sdw_slave *slave, u32
> > > addr, size_t count, u8 *val)
> > >       if (ret < 0)
> > >           return ret;
> > > -    ret = pm_runtime_get_sync(slave->bus->dev);
> > > -    if (ret < 0)
> > > -        return ret;
> > > +    if (pm_runtime_enabled(slave->bus->dev)) {
> > > +        ret = pm_runtime_get_sync(slave->bus->dev);
> > > +        if (ret < 0)
> > > +            return ret;
> > > +    }
> > >       ret = sdw_transfer(slave->bus, &msg);
> > >       pm_runtime_put(slave->bus->dev);
> 
> I should add a check in this path as well.
> 
> Thanks,
> srini
> 
> > > 
> > 

-- 
~Vinod