linux-kernel - Re: [RFC PATCH] ACPI/PCI: Fix bus range comparation in pci_mcfg

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Date:   Tue, 3 Jan 2017 07:39:33 +0100
From:   Tomasz Nowicki <tn@...ihalf.com>
To:     Zhou Wang <wangzhou1@...ilicon.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Jayachandran C <jchandra@...adcom.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        jorn Helgaas <bhelgaas@...gle.com>
Cc:     liudongdong3@...wei.com, gabriele.paoloni@...wei.com,
        linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] ACPI/PCI: Fix bus range comparation in
 pci_mcfg_lookup

On 22.12.2016 10:07, Zhou Wang wrote:
> Multiple PCIe host bridges may exists in one PCIe segment. So bus range for each
> host bridge should be in the coverage of bus range of related PCIe segment.
>
> This patch will support this kind of scenario:
>
> MCFG:
> 	bus range: 0x00~0xff.
> 	segment: 0.
> DSDT:
> 	host bridge 1:
> 		bus range: 0x00~0x1f.
> 		segment: 0.
> 	host bridge 2:
> 		bus range: 0x20~0x4f.
> 		segment: 0.
>
> Signed-off-by: Zhou Wang <wangzhou1@...ilicon.com>
> ---
>  drivers/acpi/pci_mcfg.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/pci_mcfg.c b/drivers/acpi/pci_mcfg.c
> index b5b376e..46a3e32 100644
> --- a/drivers/acpi/pci_mcfg.c
> +++ b/drivers/acpi/pci_mcfg.c
> @@ -40,11 +40,10 @@ phys_addr_t pci_mcfg_lookup(u16 seg, struct resource *bus_res)
>  	struct mcfg_entry *e;
>
>  	/*
> -	 * We expect exact match, unless MCFG entry end bus covers more than
> -	 * specified by caller.
> +	 * We expect the range in bus_res in the coverage of MCFG bus range.
>  	 */
>  	list_for_each_entry(e, &pci_mcfg_list, list) {
> -		if (e->segment == seg && e->bus_start == bus_res->start &&
> +		if (e->segment == seg && e->bus_start <= bus_res->start &&
>  		    e->bus_end >= bus_res->end)
>  			return e->addr;
>  	}
>

Looks good to me.

Reviewed-by: Tomasz Nowicki <tn@...ihalf.com>

Thanks,
Tomasz