On Tue, Sep 26, 2023 at 04:08:23PM -0500, Bjorn Helgaas wrote: > On Sun, Sep 24, 2023 at 06:07:13PM +0200, Manivannan Sadhasivam wrote: > > PCIe Gen4 supports the interconnect bandwidth of 1969 MBps. So let's add > > the bandwidth support in the driver. Otherwise, the default bandwidth of > > 985 MBps will be used. > > > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > > --- > > drivers/pci/controller/dwc/pcie-qcom.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c > > index 297442c969b6..6853123f92c1 100644 > > --- a/drivers/pci/controller/dwc/pcie-qcom.c > > +++ b/drivers/pci/controller/dwc/pcie-qcom.c > > @@ -1384,11 +1384,14 @@ static void qcom_pcie_icc_update(struct qcom_pcie *pcie) > > case 2: > > bw = MBps_to_icc(500); > > break; > > + case 3: > > + bw = MBps_to_icc(985); > > + break; > > default: > > WARN_ON_ONCE(1); > > fallthrough; > > - case 3: > > - bw = MBps_to_icc(985); > > + case 4: > > + bw = MBps_to_icc(1969); > > The bare numbers here are sort of weird. I assume they correspond to > the Supported Link Speeds Vector in Link Cap 2, and I expected them to > correspond somehow to PCIE_SPEED2MBS_ENC(), which computes the usable > PCIe bandwidth per lane. I see the ratios between 250, 500, 986, 1969 > *do* match up with the ratios of PCIE_SPEED2MBS_ENC() values, but I > don't know the PCIE_SPEED2MBS_ENC() values aren't used: > > SLS Vector PCIE_SPEED2MBS_ENC() > CLS 1: bit 0 2.5 GT/s MBps_to_icc(250) 2000 Mbps > CLS 2: bit 1 5.0 GT/s MBps_to_icc(500) 4000 Mbps > CLS 3: bit 2 8.0 GT/s MBps_to_icc(985) 7879 Mbps > CLS 4: bit 3 16.0 GT/s MBps_to_icc(1969) 15753 Mbps > > This is just my curiosity, probably no change is needed, or at most a > short comment. > You are right. I'm not aware of this macro before and yes, I can make use of it. > I do notice that pcie-qcom-ep.c uses #defines like PCIE_GEN1_BW_MBPS, > and it seems like both could use the same style. > > Also agree with Konrad that the ordering ends up looking unusual; > maybe would be more readable if the default case repeated the speed > you want instead of using the fallthrough. > Yes, that would be more readable. - Mani > > break; > > } -- மணிவண்ணன் சதாசிவம்
