On Fri, Jan 06, 2023 at 04:47:33PM +0800, guo.ziliang@xxxxxxxxxx wrote:
> From: Chen Lin <chen.lin5@xxxxxxxxxx>
> bridge base/limit(memory behind in lspci info, outbound pcie address/size)
> region is used to route outbound mem read/write transaction to ep. This
> base/limit region also may filter out inbound transactions which will
> result in inbound(eg: dma) transaction fail.
>
> For example, if bridge base/limit is [0x20000000, 0x203fffff], system ram
> is [0x20000000, 0x27ffffff]. The inbound mapping is usually 1:1 equal
> mapping. When allocated system ram for inbound tansaction is 0x20004000
> (any in bridge base/limit), this inbound transactions will be filter out.
>
> AER may report 'UnsupReq' on inbound mem read/write transactions if address
> is in this base/limit region, but not all pcie AER enabled or work well. We
> warn it also in host bridge pci address detection phase.
Is this a DT-specific thing? It sounds like it should apply to PCI
bridges in general.
> Signed-off-by: Chen Lin <chen.lin5@xxxxxxxxxx>
> ---
> drivers/pci/of.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index 196834ed44fe..82e09af6c638 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -314,6 +314,8 @@ static int devm_of_pci_get_host_bridge_resources(struct device *dev,
>
> dev_dbg(dev, "Parsing ranges property...\n");
> for_each_of_pci_range(&parser, &range) {
> + int is_ram;
> +
> /* Read next ranges element */
> if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
> range_type = "IO";
> @@ -332,6 +334,18 @@ static int devm_of_pci_get_host_bridge_resources(struct device *dev,
> if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> continue;
>
> + /*
> + * bridge base/limit(memory behind) region may filter out inbound
> + * transactions which will result in inbound(eg:dma) fail of ep.
> + * AER may report it if enabled, we warn it also.
> + */
> + is_ram = region_intersects(range.pci_addr, range.size,
> + IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
> + if (is_ram == REGION_INTERSECTS) {
> + dev_warn(dev, "%#012llx..%#012llx bridge base/limit region overlaps with system ram, may result in inbound fail\n",
> + range.pci_addr, range.pci_addr + range.size - 1);
> + }
> +
> err = of_pci_range_to_resource(&range, dev_node, &tmp_res);
> if (err)
> continue;
> --
> 2.15.2
