| Message ID | 20230924160713.217086-1-manivannan.sadhasivam@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | PCI: qcom: Add interconnect bandwidth for PCIe Gen4 | expand |
On 24.09.2023 18:07, 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@linaro.org> > --- > 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); > break; Are you adding case 4 under `default`? That looks.. bizzare.. Konrad
On 23-09-25 10:57:47, Konrad Dybcio wrote: > On 24.09.2023 18:07, 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@linaro.org> > > --- > > 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); > > break; > Are you adding case 4 under `default`? That looks.. bizzare.. That's intentional. You want it to use 1969MBps if there is a different gen value. AFAIU. > > Konrad
On 25.09.2023 12:33, Abel Vesa wrote: > On 23-09-25 10:57:47, Konrad Dybcio wrote: >> On 24.09.2023 18:07, 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@linaro.org> >>> --- >>> 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); >>> break; >> Are you adding case 4 under `default`? That looks.. bizzare.. > > That's intentional. You want it to use 1969MBps if there is a different > gen value. AFAIU. Gah right, then the commit message is wrong. Konrad
On 23-09-24 18:07:13, 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@linaro.org> Tested-by: Abel Vesa <abel.vesa@linaro.org> > --- > 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); > break; > } > > -- > 2.25.1 >
On 23-09-25 12:34:53, Konrad Dybcio wrote: > On 25.09.2023 12:33, Abel Vesa wrote: > > On 23-09-25 10:57:47, Konrad Dybcio wrote: > >> On 24.09.2023 18:07, 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@linaro.org> > >>> --- > >>> 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); > >>> break; > >> Are you adding case 4 under `default`? That looks.. bizzare.. > > > > That's intentional. You want it to use 1969MBps if there is a different > > gen value. AFAIU. > Gah right, then the commit message is wrong. Yep, should be: "Otherwise, the default bandwidth of 1969 MBps will be used." But maybe we should not default to that. Maybe we should still default to 985 MBps. > > Konrad
On 25.09.2023 12:37, Abel Vesa wrote: > On 23-09-25 12:34:53, Konrad Dybcio wrote: >> On 25.09.2023 12:33, Abel Vesa wrote: >>> On 23-09-25 10:57:47, Konrad Dybcio wrote: >>>> On 24.09.2023 18:07, 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@linaro.org> >>>>> --- >>>>> 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); >>>>> break; >>>> Are you adding case 4 under `default`? That looks.. bizzare.. >>> >>> That's intentional. You want it to use 1969MBps if there is a different >>> gen value. AFAIU. >> Gah right, then the commit message is wrong. > > Yep, should be: "Otherwise, the default bandwidth of 1969 MBps will be > used." > > But maybe we should not default to that. Maybe we should still default > to 985 MBps. Perhaps we shouldn't have a default at all.. E.g. if the gen5 bus may get clogged if we exceed gen4 limits Konrad
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@linaro.org> > --- > 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. 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. > break; > }
On Mon, Sep 25, 2023 at 12:40:34PM +0200, Konrad Dybcio wrote: > On 25.09.2023 12:37, Abel Vesa wrote: > > On 23-09-25 12:34:53, Konrad Dybcio wrote: > >> On 25.09.2023 12:33, Abel Vesa wrote: > >>> On 23-09-25 10:57:47, Konrad Dybcio wrote: > >>>> On 24.09.2023 18:07, 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@linaro.org> > >>>>> --- > >>>>> 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); > >>>>> break; > >>>> Are you adding case 4 under `default`? That looks.. bizzare.. > >>> > >>> That's intentional. You want it to use 1969MBps if there is a different > >>> gen value. AFAIU. > >> Gah right, then the commit message is wrong. > > > > Yep, should be: "Otherwise, the default bandwidth of 1969 MBps will be > > used." > > > > But maybe we should not default to that. Maybe we should still default > > to 985 MBps. > Perhaps we shouldn't have a default at all.. > > E.g. if the gen5 bus may get clogged if we exceed gen4 > limits > So the idea here is that if we happen to run this driver on a new Gen supported SoC, we have to let the user know that the interconnects are running at a lower gen speed and it needs attention. But I think we can simplify it by fixing a default bandwidth, say Gen3 and get rid of the fallthrough. And yeah, the same needs to be done for the pcie-qcom-ep driver as well. - Mani > Konrad
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@linaro.org> > > --- > > 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; > > }
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); break; }
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@linaro.org> --- drivers/pci/controller/dwc/pcie-qcom.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)