On Wed, Apr 26, 2023 at 01:55:47PM +0900, Yoshihiro Shimoda wrote:
> Add dw_pcie_link_set_max_cap_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 | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index f8926d5ec422..bdc5ebd7cd5f 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -737,6 +737,21 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
> dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, cap | link_speed);
> }
>
> +static void dw_pcie_link_set_max_cap_width(struct dw_pcie *pci, int num_lanes)
> +{
> + u32 val;
> + u8 cap;
> +
> + if (!num_lanes)
> + return;
> +
> + cap = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> + val = dw_pcie_readl_dbi(pci, cap + PCI_EXP_LNKCAP);
> + val &= ~PCI_EXP_LNKCAP_MLW;
> + val |= num_lanes << PCI_EXP_LNKSTA_NLW_SHIFT;
> + dw_pcie_writel_dbi(pci, cap + PCI_EXP_LNKCAP, val);
> +}
Just move the function body to dw_pcie_link_set_max_link_width() thus
the later method will be as coherent as possible.
Also note the duplicated code can be dropped from the pcie-tegra194.c
driver. Please submit an additional cleanup patch so the Tegra driver
author would have it reviewed.
-Serge(y)
> +
> static void dw_pcie_link_set_max_width(struct dw_pcie *pci, u32 num_lanes)
> {
> u32 val;
> @@ -1074,6 +1089,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
> dw_pcie_writel_dbi(pci, PCIE_PL_CHK_REG_CONTROL_STATUS, val);
> }
>
> + dw_pcie_link_set_max_cap_width(pci, pci->num_lanes);
> dw_pcie_link_set_max_width(pci, pci->num_lanes);
> dw_pcie_link_set_max_link_width(pci, pci->num_lanes);
> }
> --
> 2.25.1
>
