On Sun, Apr 07, 2024 at 10:07:35AM +0530, Krishna chaitanya chundru wrote:
> To access PCIe registers, PCIe BAR space, config space the CPU-PCIe
Please specify whether you are referencing PCIe host controller or endpoint
device or both.
> ICC (interconnect consumers) path should be voted otherwise it may
ICC is just 'Interconnect' unless I misunderstood.
> lead to NoC (Network on chip) timeout. We are surviving because of
> other driver vote for this path.
>
s/vote/voting
> As there is less access on this path compared to PCIe to mem path
> add minimum vote i.e 1KBps bandwidth always which is recommended
> by HW team.
>
'which is sufficient enough to keep the path active.'
> When suspending, disable this path after register space access
> is done.
>
> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxxx>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 38 ++++++++++++++++++++++++++++++----
> 1 file changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 14772edcf0d3..b4893214b2d3 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -245,6 +245,7 @@ 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;
> @@ -1409,6 +1410,9 @@ 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.
> @@ -1418,7 +1422,19 @@ 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;
> + }
> +
> + /*
> + * Since the CPU-PCIe path is only used for activities like register
Again, differentiate PCIe controller and endpoint device access.
> + * access, Config/BAR space access, HW team has recommended to use a
> + * minimal bandwidth of 1KBps just to keep the link active.
> + */
> + ret = icc_set_bw(pcie->icc_cpu, 0, kBps_to_icc(1));
> + if (ret) {
> + dev_err(pci->dev, "failed to set interconnect bandwidth for CPU-PCIe: %d\n",
> ret);
> return ret;
> }
> @@ -1448,7 +1464,7 @@ static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
>
> ret = icc_set_bw(pcie->icc_mem, 0, width * QCOM_PCIE_LINK_SPEED_TO_BW(speed));
> 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);
> }
> }
> @@ -1610,7 +1626,7 @@ 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;
> }
>
> @@ -1634,7 +1650,15 @@ static int qcom_pcie_suspend_noirq(struct device *dev)
> pcie->suspended = true;
> }
>
> - return 0;
> + /*
> + * Remove the vote for CPU-PCIe path now, since at this point onwards,
> + * no register access will be done.
> + */
Are you sure? Didn't we see late access to DBI registers on sc7280?
> + ret = icc_disable(pcie->icc_cpu);
> + if (ret)
> + dev_err(dev, "failed to disable icc path of CPU-PCIe: %d\n", ret);
s/failed to disable icc path/Failed to disable Interconnect path between CPU-PCIe
> +
> + return ret;
> }
>
> static int qcom_pcie_resume_noirq(struct device *dev)
> @@ -1642,6 +1666,12 @@ static int qcom_pcie_resume_noirq(struct device *dev)
> struct qcom_pcie *pcie = dev_get_drvdata(dev);
> int ret;
>
> + ret = icc_enable(pcie->icc_cpu);
> + if (ret) {
> + dev_err(dev, "failed to enable icc path of CPU-PCIe: %d\n", ret);
Same as above.
- Mani
--
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