Update dw_pcie_link_set_max_link_width() to set PCI_EXP_LNKCAP_MLW.
In accordance with the DW PCIe RC/EP HW manuals [1,2,3,...] aside with
the PORT_LINK_CTRL_OFF.LINK_CAPABLE and GEN2_CTRL_OFF.NUM_OF_LANES[8:0]
field there is another one which needs to be updated. It's
LINK_CAPABILITIES_REG.PCIE_CAP_MAX_LINK_WIDTH. If it isn't done at
the very least the maximum link-width capability CSR won't expose
the actual maximum capability.
[1] DesignWare Cores PCI Express Controller Databook - DWC PCIe Root Port,
Version 4.60a, March 2015, p.1032
[2] DesignWare Cores PCI Express Controller Databook - DWC PCIe Root Port,
Version 4.70a, March 2016, p.1065
[3] DesignWare Cores PCI Express Controller Databook - DWC PCIe Root Port,
Version 4.90a, March 2016, p.1057
...
[X] DesignWare Cores PCI Express Controller Databook - DWC PCIe Endpoint,
Version 5.40a, March 2019, p.1396
[X+1] DesignWare Cores PCI Express Controller Databook - DWC PCIe Root Port,
Version 5.40a, March 2019, p.1266
The commit description is suggested by Serge Semin.
Suggested-by: Serge Semin <fancer.lancer@xxxxxxxxx>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
drivers/pci/controller/dwc/pcie-designware.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 7b720bad7656..44150d34720a 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -730,7 +730,8 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
static void dw_pcie_link_set_max_link_width(struct dw_pcie *pci, u32 num_lanes)
{
- u32 lwsc, plc;
+ u32 lnkcap, lwsc, plc;
+ u8 cap;
if (!num_lanes)
return;
@@ -766,6 +767,12 @@ static void dw_pcie_link_set_max_link_width(struct dw_pcie *pci, u32 num_lanes)
}
dw_pcie_writel_dbi(pci, PCIE_PORT_LINK_CONTROL, plc);
dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, lwsc);
+
+ cap = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+ lnkcap = dw_pcie_readl_dbi(pci, cap + PCI_EXP_LNKCAP);
+ lnkcap &= ~PCI_EXP_LNKCAP_MLW;
+ lnkcap |= FIELD_PREP(PCI_EXP_LNKCAP_MLW, num_lanes);
+ dw_pcie_writel_dbi(pci, cap + PCI_EXP_LNKCAP, lnkcap);
}
void dw_pcie_iatu_detect(struct dw_pcie *pci)
--
2.25.1
