Re: [RFC PATCH] powerpc/64s: remove POWER9 DD1 support

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Mon, 2018-06-11 at 11:37 +1000, Nicholas Piggin wrote:
> 
> > > -
> > >  	/* Perform the acknowledge OS to register cycle. */
> > >  	ack = be16_to_cpu(__x_readw(__x_tima + TM_SPC_ACK_OS_REG));
> > >  
> > > @@ -105,7 +93,7 @@ static void GLUE(X_PFX,source_eoi)(u32 hw_irq,
> > > struct xive_irq_data *xd) *
> > >  		 * For LSIs, using the HW EOI cycle works around a
> > > problem
> > >  		 * on P9 DD1 PHBs where the other ESB accesses don't
> > > work
> > > -		 * properly.
> > > +		 * properly. XXX: can this be removed?
> > >  		 */
> > >  		if (xd->flags & XIVE_IRQ_FLAG_LSI)
> > >  			__x_readq(__x_eoi_page(xd) +  
> > 
> > Maybe this should be really removed or the comment changed to why it is
> > still useful?
> 
> Good point, I meant to ask Ben about that.

We should just update the comment, the game with PQ bits is not useful
for LSIs are they are automatically re-triggered in HW when still
pending. So even with no errata to work around, it's still the right
thing to do.

Cheers,
Ben.