[Skiboot] [PATCH V2] core: Add explicit 1:1 mappings in ranges properties

[Benjamin Herrenschmidt]

On Thu, 2016-02-18 at 14:37 +1100, Sam Mendoza-Jonas wrote:
> Currently skiboot adds an empty ranges property for each PCI bridge,
> representing a 1:1 mapping, which the kernel can later update if
> needed.
> However this does not appear to be the case, which leads to an issue
> in
> the kernel where the translation of assigned-addresses properties is
> mishandled and prematurely drops the PCI memory flags (ie. the first
> cell of an address).
> 
> Instead, explicitly describe a 1:1 mapping in each bridge's ranges
> property, allowing assigned-addresses to be properly handled.
> 
> Signed-off-by: Sam Mendoza-Jonas <sam at mendozajonas.com>

Assuming you tested it with offb

Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

> ---
> V2: Use a single 64-bit range with proper size, and add an additional
> comment about the size.
> 
>  core/pci.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/core/pci.c b/core/pci.c
> index 03d5a35..c51c838 100644
> --- a/core/pci.c
> +++ b/core/pci.c
> @@ -1321,6 +1321,13 @@ static void pci_add_one_node(struct phb *phb,
> struct pci_device *pd,
>  	uint32_t rev_class, vdid;
>  	uint32_t reg[5];
>  	uint8_t intpin;
> +	const uint32_t ranges_direct[] = {
> +				/* 64-bit direct mapping. We know
> the bridges
> +				 * don't cover the entire address
> space so
> +				 * use 0xf00... as a good
> compromise. */
> +				0x02000000, 0x0, 0x0,
> +				0x02000000, 0x0, 0x0,
> +				0xf0000000, 0x0};
>  
>  	pci_cfg_read32(phb, pd->bdfn, 0, &vdid);
>  	pci_cfg_read32(phb, pd->bdfn, PCI_CFG_REV_ID, &rev_class);
> @@ -1414,12 +1421,12 @@ static void pci_add_one_node(struct phb *phb,
> struct pci_device *pd,
>  	 */
>  	pci_std_swizzle_irq_map(np, pd, lstate, swizzle);
>  
> -	/* We do an empty ranges property for now, we haven't setup
> any
> -	 * bridge windows, the kernel will deal with that
> -	 *
> -	 * XXX The kernel should probably fix that up
> +	/* Parts of the OF address translation in the kernel will
> fail to
> +	 * correctly translate a PCI address if translating a 1:1
> mapping
> +	 * (ie. an empty ranges property).
> +	 * Instead add a ranges property that explicitly translates
> 1:1.
>  	 */
> -	dt_add_property(np, "ranges", NULL, 0);
> +	dt_add_property(np, "ranges", ranges_direct,
> sizeof(ranges_direct));
>  
>  	list_for_each(&pd->children, child, link)
>  		pci_add_one_node(phb, child, np, lstate, swizzle);