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Subject: Re: [PATCH] powerpc/powernv: retrieve m64_bar_idx from device node
From: Michael Ellerman <mpe@ellerman.id.au>
To: Wei Yang <weiyang@linux.vnet.ibm.com>, aik@ozlabs.ru,
 benh@kernel.crashing.org
Cc: linuxppc-dev@ozlabs.org
Date: Wed, 21 Oct 2015 18:52:51 +1100
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On Wed, 2015-10-21 at 15:17 +0800, Wei Yang wrote:

> Count of M64 BAR would differ with the evolution of hardware.
> 
> This patch retieves this count from device node instead of a hard coded
> value.
> 
> Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
> ---
>  arch/powerpc/platforms/powernv/pci-ioda.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 5c65d8f..4635d25 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -368,6 +368,7 @@ static void __init pnv_ioda_parse_m64_window(struct pnv_phb *phb)
>  	struct resource *res;
>  	const u32 *r;
>  	u64 pci_addr;
> +	const __be32 *prop32;
>  
>  	/* FIXME: Support M64 for P7IOC */
>  	if (phb->type != PNV_PHB_IODA2) {
> @@ -402,7 +403,11 @@ static void __init pnv_ioda_parse_m64_window(struct pnv_phb *phb)
>  			res->start, res->end, pci_addr);
>  
>  	/* Use last M64 BAR to cover M64 window */
> -	phb->ioda.m64_bar_idx = 15;
> +	prop32 = of_get_property(dn, "ibm,opal-m64-count", NULL);
> +	if (prop32)
> +		phb->ioda.m64_bar_idx = be32_to_cpup(prop32) - 1;
> +	else
> +		phb->ioda.m64_bar_idx = 15;

Please use of_property_read_u32() instead of using of_get_property() directly.

Also the "-1" is a bit unclear, I think it would be clearer if you did
something like:

	if (of_property_read_u32(dn, "ibm,opal-m64-count", &count))
		count = 16;

	/* Use last M64 BAR to cover M64 window */
	phb->ioda.m64_bar_idx = count - 1;


cheers