Re: [PATCH v5 08/11] powerpc/pseries/iommu: Update remove_dma_window() to accept property name

[Alexey Kardashevskiy]

On 17/08/2021 16:12, Leonardo Brás wrote:
> On Tue, 2021-08-17 at 02:59 -0300, Leonardo Brás wrote:
> > Hello Fred, thanks for the feedback!
> >
> > On Tue, 2021-07-20 at 19:51 +0200, Frederic Barrat wrote:
> > > On 16/07/2021 10:27, Leonardo Bras wrote:
> > > > Update remove_dma_window() so it can be used to remove DDW with a
> > > > given
> > > > property name.
> > > >
> > > > This enables the creation of new property names for DDW, so we
> > > > can
> > > > have different usage for it, like indirect mapping.
> > > >
> > > > Signed-off-by: Leonardo Bras <leobras.c@xxxxxxxxx>
> > > > Reviewed-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> > > > ---
> > > >    arch/powerpc/platforms/pseries/iommu.c | 21 +++++++++++--------
> > > > --
> > > >    1 file changed, 11 insertions(+), 10 deletions(-)
> > > >
> > > > diff --git a/arch/powerpc/platforms/pseries/iommu.c
> > > > b/arch/powerpc/platforms/pseries/iommu.c
> > > > index 108c3dcca686..17c6f4706e76 100644
> > > > --- a/arch/powerpc/platforms/pseries/iommu.c
> > > > +++ b/arch/powerpc/platforms/pseries/iommu.c
> > > > @@ -830,31 +830,32 @@ static void remove_dma_window(struct
> > > > device_node *np, u32 *ddw_avail,
> > > >                          np, ret,
> > > > ddw_avail[DDW_REMOVE_PE_DMA_WIN],
> > > > liobn);
> > > >    }
> > > >    
> > > > -static void remove_ddw(struct device_node *np, bool remove_prop)
> > > > +static int remove_ddw(struct device_node *np, bool remove_prop,
> > > > const char *win_name)
> > > >    {
> > >
> > >
> > > Why switch to returning an int? None of the callers check it.
> >
> > IIRC, in a previous version it did make sense, which is not the case
> > anymore. I will revert this.
> >
> > Thanks!
>
> Oh, sorry about that, it is in fact still needed:


Then you should have added it in 10/11.

> It will make sense in patch v5 10/11:
> On iommu_reconfig_notifier(), if (action == OF_RECONFIG_DETACH_NODE),
> we need to remove a DDW if it exists.
>
> As there may be different window names, it tests for DIRECT64_PROPNAME,
> and if it's not found, it tests for DMA64_PROPNAME.
>
> This approach will skip scanning for DMA64_PROPNAME if
> DIRECT64_PROPNAME was found, as both may not exist in the same node.
> But for this approach to work we need remove_ddw() to return error if
> the property is not found.
>
> Does it make sense? or should I just test for both?

Or you could just try removing both without checking the return code, it 
is one extra of_find_property in very rare code path. Not worth 
reposting though imho. (sorry I was off last week, catching up). Thanks,



--
Alexey