On Wed, Jan 14, 2026 at 12:54:37PM +0900, Koichiro Den wrote:
> I realized that I missed one case in v7.
>
> I think dw_pcie_ep_clear_ib_maps() should also be called from
> dw_pcie_ep_ib_atu_bar() to tear down any existing inbound mappings for the
> same BAR before re-programming it in BAR Match Mode.
>
> This matters when updating inbound mappings for a BAR without resetting the
> BAR in between. There are four possible transition patterns, and pattern #4
> below was overlooked:
>
> 1. BAR Match Mode -> BAR Match Mode
> As the current implementation does, the mapping is simply updated
> (with the same atu index)
>
> 2. BAR Match Mode -> Address Match Mode
> This patch series already ensures the old BAR Match mapping is
> torn down before reprogramming.
>
> 3. Address Match Mode -> Address Match Mode
> Likewise, existing Address Match mappings are cleared first.
>
> 4. Address Match Mode -> BAR Match Mode
> This case was not handled. The change below adds the missing
> teardown so that stale Address Match mappings do not remain active.
>
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -148,9 +148,12 @@ static int dw_pcie_ep_ib_atu_bar(struct dw_pcie_ep
> *ep, u8 func_no, int type,
> u32 free_win;
> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>
> - if (!ep->bar_to_atu[bar])
> + if (!ep->bar_to_atu[bar]) {
> + /* Tear down existing mappings before (re)programming. */
> + dw_pcie_ep_clear_ib_maps(ep, bar);
> +
> free_win = find_first_zero_bit(ep->ib_window_map,
> pci->num_ib_windows);
> - else
> + } else
> free_win = ep->bar_to_atu[bar] - 1;
If one of the branches has braces, both branches should have braces:
https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
>
> Unless there are objections, I'll include this fix in v8.
Isn't it easier/cleaner if we call dw_pcie_ep_clear_ib_maps() in
dw_pcie_ep_set_bar(), rather than calling it in both dw_pcie_ep_ib_atu_addr()
and dw_pcie_ep_ib_atu_bar() ?
dw_pcie_ep_set_bar() knows the condition if we are dynamically reprogramming
a BAR or not, and all the four cases are when dynamically reprogramming a BAR.
I.e. instead of adding additional code to dw_pcie_ep_ib_atu_bar(), we do
something like:
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c
b/drivers/pci/controller/dwc/pcie-designware-ep.c
index b2ea2c2c986f..63ae5471fe13 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -318,9 +318,6 @@ static int dw_pcie_ep_ib_atu_addr(struct dw_pcie_ep *ep, u8
func_no, int type,
return -EINVAL;
}
- /* Tear down any existing mappings before (re)programming. */
- dw_pcie_ep_clear_ib_maps(ep, bar);
-
for (i = 0; i < epf_bar->num_submap; i++) {
off = submap[i].offset;
size = submap[i].size;
@@ -571,6 +568,9 @@ 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;
+ 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.
