Re: [PATCH 10/15] swiotlb: add a SWIOTLB_ANY flag to lift the low memory restriction

[Christoph Hellwig]

On Wed, Apr 06, 2022 at 08:25:32PM -0400, Konrad Rzeszutek Wilk wrote:
> > diff --git a/arch/powerpc/platforms/pseries/svm.c 
> > b/arch/powerpc/platforms/pseries/svm.c
> > index c5228f4969eb2..3b4045d508ec8 100644
> > --- a/arch/powerpc/platforms/pseries/svm.c
> > +++ b/arch/powerpc/platforms/pseries/svm.c
> > @@ -28,7 +28,7 @@ static int __init init_svm(void)
> >      * need to use the SWIOTLB buffer for DMA even if dma_capable() says
> >      * otherwise.
> >      */
> > -   swiotlb_force = SWIOTLB_FORCE;
> > +   ppc_swiotlb_flags |= SWIOTLB_ANY | SWIOTLB_FORCE;
> 
> This is the only place you set the ppc_swiotlb_flags.. so I wonder why
> the '|=' instead of just '=' ?

Preparing for setting others and not clobbering the value.