Re: [PATCH v9 04/22] powerpc/powernv: Increase PE# capacity

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On 05/03/2016 11:22 PM, Gavin Shan wrote:
Each PHB maintains an array helping to translate 2-bytes Request
ID (RID) to PE# with the assumption that PE# takes one byte, meaning
that we can't have more than 256 PEs. However, pci_dn->pe_number
already had 4-bytes for the PE#.

Can you possibly have more than 256 PEs? Or exactly 256? What patch in this series makes use of it?

I probably asked but do not remember the answer :)

Looks like waste of memory - you only used a small fraction of pe_rmap[0x10000] and now the waste is quadrupled.



This extends the PE# capacity for every PHB. After that, the PE number
is represented by 4-bytes value. Then we can reuse IODA_INVALID_PE to
check the PE# in phb->pe_rmap[] is valid or not.

Looks like using IODA_INVALID_PE is the only reason for this patch.



Signed-off-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Daniel Axtens <dja@xxxxxxxxxx>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 6 +++++-
 arch/powerpc/platforms/powernv/pci.h      | 7 ++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index cbd4c0b..cf96cb5 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -768,7 +768,7 @@ static int pnv_ioda_deconfigure_pe(struct pnv_phb *phb, struct pnv_ioda_pe *pe)

 	/* Clear the reverse map */
 	for (rid = pe->rid; rid < rid_end; rid++)
-		phb->ioda.pe_rmap[rid] = 0;
+		phb->ioda.pe_rmap[rid] = IODA_INVALID_PE;

 	/* Release from all parents PELT-V */
 	while (parent) {
@@ -3406,6 +3406,10 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 	if (prop32)
 		phb->ioda.reserved_pe_idx = be32_to_cpup(prop32);

+	/* Invalidate RID to PE# mapping */
+	for (segno = 0; segno < ARRAY_SIZE(phb->ioda.pe_rmap); segno++)
+		phb->ioda.pe_rmap[segno] = IODA_INVALID_PE;
+
 	/* Parse 64-bit MMIO range */
 	pnv_ioda_parse_m64_window(phb);

diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 904f60b..80f5326 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -156,11 +156,8 @@ struct pnv_phb {
 		struct list_head	pe_list;
 		struct mutex            pe_list_mutex;

-		/* Reverse map of PEs, will have to extend if
-		 * we are to support more than 256 PEs, indexed
-		 * bus { bus, devfn }
-		 */
-		unsigned char		pe_rmap[0x10000];
+		/* Reverse map of PEs, indexed by {bus, devfn} */
+		unsigned int		pe_rmap[0x10000];

 		/* TCE cache invalidate registers (physical and
 		 * remapped)



--
Alexey
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