On Wed, Sep 04, 2024 at 11:30:08AM +0200, Johan Hovold wrote:
> 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) {
>
Well I was trying to catch the error value here because if neither driver nor
platform limits the max link speed, this would have -EINVAL (returned by
of_pci_get_max_link_speed()).
But logically it makes sense to use 'pci->max_link_speed < 1' since anything
below value 1 is an invalid value.
Will change it.
- Mani
> 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>
--
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