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Message-ID: <aXHsd7-WWAGyhy_w@ryzen>
Date: Thu, 22 Jan 2026 10:23:03 +0100
From: Niklas Cassel <cassel@...nel.org>
To: Koichiro Den <den@...inux.co.jp>
Cc: jingoohan1@...il.com, mani@...nel.org, lpieralisi@...nel.org,
kwilczynski@...nel.org, robh@...nel.org, bhelgaas@...gle.com,
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Subject: Re: [PATCH v9 4/5] PCI: dwc: ep: Support BAR subrange inbound
mapping via Address Match Mode iATU
On Thu, Jan 22, 2026 at 05:49:08PM +0900, Koichiro Den wrote:
> Extend dw_pcie_ep_set_bar() to support inbound mappings for BAR
> subranges using Address Match Mode IB iATU when pci_epf_bar.num_submap
> is non-zero.
>
> Rename the existing BAR-match helper into dw_pcie_ep_ib_atu_bar() and
> introduce dw_pcie_ep_ib_atu_addr() for Address Match Mode. When
> num_submap is non-zero, read the assigned BAR base address and program
> one inbound iATU window per subrange. Validate the submap array before
> programming:
> - each subrange is aligned to pci->region_align
> - subranges cover the whole BAR (no gaps and no overlaps)
> - subranges are sorted in ascending order by offset
>
> Track Address Match Mode mappings and tear them down on clear_bar() and
> on set_bar() error paths to avoid leaving half-programmed state or
> untranslated BAR holes.
>
> Advertise this capability by extending the common feature bit
> initializer macro (DWC_EPC_COMMON_FEATURES).
>
> This enables multiple inbound windows within a single BAR, which is
> useful on platforms where usable BARs are scarce but EPFs need multiple
> inbound regions.
>
> Reviewed-by: Frank Li <Frank.Li@....com>
> Signed-off-by: Koichiro Den <den@...inux.co.jp>
> ---
> @@ -331,6 +503,13 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> ep->epf_bar[bar]->flags != flags)
> return -EINVAL;
>
> + /*
> + * When dynamically changing a BAR, tear down any existing
> + * mappings before re-programming.
> + */
> + if (ep->epf_bar[bar]->num_submap || epf_bar->num_submap)
> + dw_pcie_ep_clear_ib_maps(ep, bar);
> +
> /*
> * When dynamically changing a BAR, skip writing the BAR reg, as
> * that would clear the BAR's PCI address assigned by the host.
> @@ -369,8 +548,12 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
> else
> type = PCIE_ATU_TYPE_IO;
>
> - ret = dw_pcie_ep_inbound_atu(ep, func_no, type, epf_bar->phys_addr, bar,
> - size);
> + if (epf_bar->num_submap)
> + ret = dw_pcie_ep_ib_atu_addr(ep, func_no, type, epf_bar);
> + else
> + ret = dw_pcie_ep_ib_atu_bar(ep, func_no, type,
> + epf_bar->phys_addr, bar, size);
If someone calls set_bar() with a submap, without having called set_bar() first
without a submap, we will still call dw_pcie_ep_ib_atu_addr() here.
To make sure that dw_pcie_ep_ib_atu_addr() cannot be called without already
having a BAR configured, to we perhaps want something like:
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 0567552b784c..fe26b7f7b212 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -487,6 +487,9 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
if ((flags & PCI_BASE_ADDRESS_MEM_TYPE_64) && (bar & 1))
return -EINVAL;
+ if (!ep->epf_bar[bar] && epf_bar->num_submap)
+ return -EINVAL;
+
/*
* Certain EPF drivers dynamically change the physical address of a BAR
* (i.e. they call set_bar() twice, without ever calling clear_bar(), as
or
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 0567552b784c..8aeaa6fe53f9 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -475,6 +475,7 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
struct dw_pcie_ep *ep = epc_get_drvdata(epc);
struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
enum pci_barno bar = epf_bar->barno;
+ bool use_addr_match_mode = false;
size_t size = epf_bar->size;
enum pci_epc_bar_type bar_type;
int flags = epf_bar->flags;
@@ -510,6 +511,9 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
if (ep->epf_bar[bar]->num_submap || epf_bar->num_submap)
dw_pcie_ep_clear_ib_maps(ep, bar);
+ if (epf_bar->num_submap)
+ use_addr_match_mode = true;
+
/*
* When dynamically changing a BAR, skip writing the BAR reg, as
* that would clear the BAR's PCI address assigned by the host.
@@ -548,7 +552,7 @@ static int dw_pcie_ep_set_bar(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
else
type = PCIE_ATU_TYPE_IO;
- if (epf_bar->num_submap)
+ if (use_addr_match_mode)
ret = dw_pcie_ep_ib_atu_addr(ep, func_no, type, epf_bar);
else
ret = dw_pcie_ep_ib_atu_bar(ep, func_no, type,
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