On Mon, Mar 27, 2023 at 07:08:24PM +0530, Manivannan Sadhasivam wrote:
> During the system suspend, vote for minimal interconnect bandwidth and
> also turn OFF the resources like clock and PHY if there are no active
> devices connected to the controller. For the controllers with active
> devices, the resources are kept ON as removing the resources will
> trigger access violation during the late end of suspend cycle as kernel
> tries to access the config space of PCIe devices to mask the MSIs.
>
> Also, it is not desirable to put the link into L2/L3 state as that
> implies VDD supply will be removed and the devices may go into powerdown
> state. This will affect the lifetime of storage devices like NVMe.
>
> And finally, during resume, turn ON the resources if the controller was
> truly suspended (resources OFF) and update the interconnect bandwidth
> based on PCIe Gen speed.
>
> Suggested-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> Acked-by: Dhruva Gole <d-gole@xxxxxx>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 62 ++++++++++++++++++++++++++
> 1 file changed, 62 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index a232b04af048..f33df536d9be 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -227,6 +227,7 @@ struct qcom_pcie {
> struct gpio_desc *reset;
> struct icc_path *icc_mem;
> const struct qcom_pcie_cfg *cfg;
> + bool suspended;
> };
>
> #define to_qcom_pcie(x) dev_get_drvdata((x)->dev)
> @@ -1820,6 +1821,62 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> return ret;
> }
>
> +static int qcom_pcie_suspend_noirq(struct device *dev)
> +{
> + struct qcom_pcie *pcie = dev_get_drvdata(dev);
> + int ret;
> +
> + /*
> + * Set minimum bandwidth required to keep data path functional during
> + * suspend.
> + */
> + ret = icc_set_bw(pcie->icc_mem, 0, MBps_to_icc(250));
This isn't really the minimum bandwidth you're setting here.
I think you said off list that you didn't see real impact reducing the
bandwidth, but have you tried requesting the real minimum which would be
kBps_to_icc(1)?
Doing so works fine here with both the CRD and X13s and may result in
some further power savings.
> + if (ret) {
> + dev_err(dev, "Failed to set interconnect bandwidth: %d\n", ret);
> + return ret;
> + }
Johan
