Re: [PATCH v6 3/6] PCI: qcom: Add missing icc bandwidth vote for cpu to PCIe path

[Krishna Chaitanya Chundru]

On 1/12/2024 10:17 PM, Bjorn Helgaas wrote:
> Capitalize "ICC" and "CPU" to make the subject easier to read.
> "Missing" might be superfluous in the subject?  It would be nice to
> have the ICC expansion once in the commit log as a hook for newbies
> like me :)
Sure I will change a suggested in next patch series.
> On Fri, Jan 12, 2024 at 07:52:02PM +0530, Krishna chaitanya chundru wrote:
> > CPU-PCIe path consits for registers PCIe BAR space, config space.
> > As there is less access on this path compared to pcie to mem path
> > add minimum vote i.e GEN1x1 bandwidth always.
>
> "GEN1x1" is unnecessarily ambiguous, and the spec recommends avoiding
> it (PCIe r6.0, sec 1.2).  Use the actual bandwidth numbers instead.
>
> "PCIe" to match above.  Also below in comments and messages.
ACK.
> > In suspend remove the cpu vote after register space access is done.
>
> "CPU" to match above.
ACK
> > Fixes: c4860af88d0c ("PCI: qcom: Add basic interconnect support")
> > cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> > ---
> >   drivers/pci/controller/dwc/pcie-qcom.c | 31 +++++++++++++++++++++++++++++--
> >   1 file changed, 29 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> > index 11c80555d975..035953f0b6d8 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > @@ -240,6 +240,7 @@ struct qcom_pcie {
> >   	struct phy *phy;
> >   	struct gpio_desc *reset;
> >   	struct icc_path *icc_mem;
> > +	struct icc_path *icc_cpu;
> >   	const struct qcom_pcie_cfg *cfg;
> >   	struct dentry *debugfs;
> >   	bool suspended;
> > @@ -1372,6 +1373,9 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
> >   	if (IS_ERR(pcie->icc_mem))
> >   		return PTR_ERR(pcie->icc_mem);
> >   
> > +	pcie->icc_cpu = devm_of_icc_get(pci->dev, "cpu-pcie");
> > +	if (IS_ERR(pcie->icc_cpu))
> > +		return PTR_ERR(pcie->icc_cpu);
> >   	/*
> >   	 * Some Qualcomm platforms require interconnect bandwidth constraints
> >   	 * to be set before enabling interconnect clocks.
> > @@ -1381,7 +1385,18 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
> >   	 */
> >   	ret = icc_set_bw(pcie->icc_mem, 0, QCOM_PCIE_LINK_SPEED_TO_BW(1));
> >   	if (ret) {
> > -		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
> > +		dev_err(pci->dev, "failed to set interconnect bandwidth for pcie-mem: %d\n",
> > +			ret);
> > +		return ret;
> > +	}
> > +
> > +	/*
> > +	 * The config space, BAR space and registers goes through cpu-pcie path.
> > +	 * Set peak bandwidth to single-lane Gen1 for this path all the time.
>
> Numbers instead of "Gen1".
ACK

-Krishna Chaitanya.
> > +	 */
> > +	ret = icc_set_bw(pcie->icc_cpu, 0, QCOM_PCIE_LINK_SPEED_TO_BW(1));
> > +	if (ret) {
> > +		dev_err(pci->dev, "failed to set interconnect bandwidth for cpu-pcie: %d\n",
> >   			ret);
> >   		return ret;
> >   	}
> > @@ -1573,7 +1588,7 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
> >   	 */
> >   	ret = icc_set_bw(pcie->icc_mem, 0, kBps_to_icc(1));
> >   	if (ret) {
> > -		dev_err(dev, "Failed to set interconnect bandwidth: %d\n", ret);
> > +		dev_err(dev, "Failed to set interconnect bandwidth for pcie-mem: %d\n", ret);
> >   		return ret;
> >   	}
> >   
> > @@ -1597,6 +1612,12 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
> >   		pcie->suspended = true;
> >   	}
> >   
> > +	/* Remove cpu path vote after all the register access is done */
> > +	ret = icc_set_bw(pcie->icc_cpu, 0, 0);
> > +	if (ret) {
> > +		dev_err(dev, "failed to set interconnect bandwidth for cpu-pcie: %d\n", ret);
> > +		return ret;
> > +	}
> >   	return 0;
> >   }
> >   
> > @@ -1605,6 +1626,12 @@ static int qcom_pcie_resume_noirq(struct device *dev)
> >   	struct qcom_pcie *pcie = dev_get_drvdata(dev);
> >   	int ret;
> >   
> > +	ret = icc_set_bw(pcie->icc_cpu, 0, QCOM_PCIE_LINK_SPEED_TO_BW(1));
> > +	if (ret) {
> > +		dev_err(dev, "failed to set interconnect bandwidth for cpu-pcie: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> >   	if (pcie->suspended) {
> >   		ret = qcom_pcie_host_init(&pcie->pci->pp);
> >   		if (ret)
> >
> > --
> > 2.42.0