On Wed, Sep 04, 2024 at 12:41:58PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
>
> Currently, dw_pcie::max_link_speed has a valid value only if the controller
> driver restricts the maximum link speed in the driver or if the platform
> does so in the devicetree using the 'max-link-speed' property.
>
> But having the maximum supported link speed of the platform would be
> helpful for the vendor drivers to configure any link specific settings.
> So in the case of non-valid value in dw_pcie::max_link_speed, just cache
> the hardware default value from Link Capability register.
>
> While at it, let's also remove the 'max_link_speed' argument to the
> dw_pcie_link_set_max_speed() function since the value can be retrieved
> within the function.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-designware.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 86c49ba097c6..0704853daa85 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -687,16 +687,27 @@ void dw_pcie_upconfig_setup(struct dw_pcie *pci)
> }
> EXPORT_SYMBOL_GPL(dw_pcie_upconfig_setup);
>
> -static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 max_link_speed)
> +static void dw_pcie_link_set_max_speed(struct dw_pcie *pci)
> {
> u32 cap, ctrl2, link_speed;
> u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
>
> cap = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +
> + /*
> + * Even if the platform doesn't want to limit the maximum link speed,
> + * just cache the hardware default value so that the vendor drivers can
> + * use it to do any link specific configuration.
> + */
> + if (pci->max_link_speed < 0) {
This should be
if (pci->max_link_speed < 1) {
but the patch works as-is because of the default case in the switch
below which falls back to PCI_EXP_LNKCAP_SLS.
> + pci->max_link_speed = FIELD_GET(PCI_EXP_LNKCAP_SLS, cap);
> + return;
> + }
> +
> ctrl2 = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCTL2);
> ctrl2 &= ~PCI_EXP_LNKCTL2_TLS;
>
> - switch (pcie_link_speed[max_link_speed]) {
> + switch (pcie_link_speed[pci->max_link_speed]) {
> case PCIE_SPEED_2_5GT:
> link_speed = PCI_EXP_LNKCTL2_TLS_2_5GT;
> break;
> @@ -1058,8 +1069,7 @@ void dw_pcie_setup(struct dw_pcie *pci)
> {
> u32 val;
>
> - if (pci->max_link_speed > 0)
> - dw_pcie_link_set_max_speed(pci, pci->max_link_speed);
> + dw_pcie_link_set_max_speed(pci);
With the above fixed:
Reviewed-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
