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

From: Alexey Kardashevskiy <[email-masked]>
Date: Wed, 10 Jun 2015 14:41:13 +1000

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;

> +
>   	/* 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.

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

-- 
Alexey