powerpc/powernv/pci: Add explicit tracking of the DMA setup state

There's an optimisation in the PE setup which skips performing DMA
setup for a PE if we only have bridges in a PE. The assumption being
that only "real" devices will DMA to system memory, which is probably
fair. However, if we start off with only bridge devices in a PE then
add a non-bridge device the new device won't be able to use DMA because
we never configured it.

Fix this (admittedly pretty weird) edge case by tracking whether we've done
the DMA setup for the PE or not. If a non-bridge device is added to the PE
(via rescan or hotplug, or whatever) we can set up DMA on demand.

This also means the only remaining user of the old "DMA Weight" code is
the IODA1 DMA setup code that it was originally added for, which is good.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200722065715.1432738-3-oohall@gmail.com

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 0727dec9a0d1..6aa6aefb637d 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -87,6 +87,13 @@ struct pnv_ioda_pe {
 	bool			tce_bypass_enabled;
 	uint64_t		tce_bypass_base;
 
+	/*
+	 * Used to track whether we've done DMA setup for this PE or not. We
+	 * want to defer allocating TCE tables, etc until we've added a
+	 * non-bridge device to the PE.
+	 */
+	bool			dma_setup_done;
+
 	/* MSIs. MVE index is identical for for 32 and 64 bit MSI
 	 * and -1 if not supported. (It's actually identical to the
 	 * PE number)