Patch "PCI: dwc: endpoint: Fix advertised resizable BAR size" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    PCI: dwc: endpoint: Fix advertised resizable BAR size

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-dwc-endpoint-fix-advertised-resizable-bar-size.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit cfd1fca9e85950b15aabf42bf1604ba94264e049
Author: Niklas Cassel <cassel@xxxxxxxxxx>
Date:   Thu Mar 7 12:15:20 2024 +0100

    PCI: dwc: endpoint: Fix advertised resizable BAR size
    
    [ Upstream commit 72e34b8593e08a0ee759b7a038e0b178418ea6f8 ]
    
    The commit message in commit fc9a77040b04 ("PCI: designware-ep: Configure
    Resizable BAR cap to advertise the smallest size") claims that it modifies
    the Resizable BAR capability to only advertise support for 1 MB size BARs.
    
    However, the commit writes all zeroes to PCI_REBAR_CAP (the register which
    contains the possible BAR sizes that a BAR be resized to).
    
    According to the spec, it is illegal to not have a bit set in
    PCI_REBAR_CAP, and 1 MB is the smallest size allowed.
    
    Set bit 4 in PCI_REBAR_CAP, so that we actually advertise support for a
    1 MB BAR size.
    
    Before:
            Capabilities: [2e8 v1] Physical Resizable BAR
                    BAR 0: current size: 1MB
                    BAR 1: current size: 1MB
                    BAR 2: current size: 1MB
                    BAR 3: current size: 1MB
                    BAR 4: current size: 1MB
                    BAR 5: current size: 1MB
    After:
            Capabilities: [2e8 v1] Physical Resizable BAR
                    BAR 0: current size: 1MB, supported: 1MB
                    BAR 1: current size: 1MB, supported: 1MB
                    BAR 2: current size: 1MB, supported: 1MB
                    BAR 3: current size: 1MB, supported: 1MB
                    BAR 4: current size: 1MB, supported: 1MB
                    BAR 5: current size: 1MB, supported: 1MB
    
    Fixes: fc9a77040b04 ("PCI: designware-ep: Configure Resizable BAR cap to advertise the smallest size")
    Link: https://lore.kernel.org/linux-pci/20240307111520.3303774-1-cassel@xxxxxxxxxx
    Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
    Signed-off-by: Krzysztof Wilczyński <kwilczynski@xxxxxxxxxx>
    Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx> # 5.2
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index fcb1fdb22ffbc..fc92d30a0ad99 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -658,8 +658,13 @@ int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 		nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
 			PCI_REBAR_CTRL_NBAR_SHIFT;
 
+		/*
+		 * PCIe r6.0, sec 7.8.6.2 require us to support at least one
+		 * size in the range from 1 MB to 512 GB. Advertise support
+		 * for 1 MB BAR size only.
+		 */
 		for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
-			dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
+			dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, BIT(4));
 	}
 
 	dw_pcie_setup(pci);