Subject: Re: [PATCH v5 11/42] powerpc/powernv: Increase PE# capacity

From: Gavin Shan <[email-masked]>
Date: Wed, 10 Jun 2015 16:18:25 +1000

On Wed, Jun 10, 2015 at 02:41:13PM +1000, Alexey Kardashevskiy wrote:
>On 06/04/2015 04:41 PM, Gavin Shan wrote:
>>Each PHB maintains an array helping to translate RID (Request
>>ID) to PE# with the assumption that PE# takes 8 bits, indicating
>>that we can't have more than 256 PEs. However, pci_dn->pe_number
>>already had 4-bytes for the PE#.
>>
>>The patch extends the PE# capacity so that each of them will be
>>4-bytes long. Then we can use IODA_INVALID_PE to check one entry
>>in phb->pe_rmap[] is valid or not.
>>
>>Signed-off-by: Gavin Shan <[email-masked]>
>>---
>>v5:
>>   * Split from [PATCH v5 v4 06/21]
>>---
>>  arch/powerpc/platforms/powernv/pci-ioda.c | 5 ++++-
>>  arch/powerpc/platforms/powernv/pci.h      | 5 ++---
>>  2 files changed, 6 insertions(+), 4 deletions(-)
>>
>>diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>>index 2087c5c..d8b0ef5 100644
>>--- a/arch/powerpc/platforms/powernv/pci-ioda.c
>>+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>>@@ -840,7 +840,7 @@ 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) {
>>@@ -3303,6 +3303,9 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
>>  	if (prop32)
>>  		phb->ioda.reserved_pe = be32_to_cpup(prop32);
>>
>>+	/* Invalidate RID to PE# mapping */
>>+	memset(phb->ioda.pe_rmap, 0xff, sizeof(phb->ioda.pe_rmap));
>
>
>Above you assign IODA_INVALID_PE in a loop and here you just do 0xff for the
>entire array. Have a loop here too and assign IODA_INVALID_PE to every entry:
>for (i = 0; i < ARRAY_SIZE(phb->ioda.pe_rmap); ++i)
>	phb->ioda.pe_rmap[i] = IODA_INVALID_PE;
>

Yeah, will change accordingly.

>>+
>>  	/* 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 94ef1df..590f778 100644
>>--- a/arch/powerpc/platforms/powernv/pci.h
>>+++ b/arch/powerpc/platforms/powernv/pci.h
>>@@ -175,11 +175,10 @@ 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
>>+			/* Reverse map of PEs, indexed by
>>  			 * bus { bus, devfn }
>>  			 */
>>-			unsigned char		pe_rmap[0x10000];
>>+			int			pe_rmap[0x10000];
>
>
>Most time most of the array will be empty and it is 256K per PHB... I
>understand we have quite a lot of RAM but still.
>

Indeed, I'll think about how to save memory here, but not in this
patchset.

>>
>>  			/* Number of 32-bit DMA segments */
>>  			unsigned long		dma32_segcount;
>>

Thanks,
Gavin