Re: [PATCH 2/3] PCI: dwc: qcom: Set suspend_poweroff flag for SC7280

Bjorn Helgaas
2022-05-16T20:20:01Z

On Fri, May 13, 2022 at 04:30:26PM +0530, Manivannan Sadhasivam wrote:
> For aggressive power saving on SC7280 SoCs, the power for the PCI devices
> will be taken off during system suspend. Hence, notify the same to the
> PCI device drivers using "suspend_poweroff" flag so that the drivers can
> prepare the PCI devices to handle the poweroff and recover them during
> resume.

No doubt "power ... will be taken off during system suspend" is true,
but this isn't very informative. Is this a property of SC7280? A
choice made by the SC7280 driver? Why is this not applicable to other
systems?

> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 6ab90891801d..4b0ad2827f8f 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -199,6 +199,7 @@ struct qcom_pcie_cfg {
> unsigned int has_ddrss_sf_tbu_clk:1;
> unsigned int has_aggre0_clk:1;
> unsigned int has_aggre1_clk:1;
> + unsigned int suspend_poweroff:1;
> };
>
> struct qcom_pcie {
> @@ -1220,6 +1221,10 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
> if (pcie->cfg->pipe_clk_need_muxing)
> clk_set_parent(res->pipe_clk_src, res->ref_clk_src);
>
> + /* Indicate PCI device drivers that the power will be taken off during system suspend */
> + if (pcie->cfg->suspend_poweroff)
> + pci->pp.bridge->suspend_poweroff = true;
> +
> ret = clk_bulk_prepare_enable(res->num_clks, res->clks);
> if (ret < 0)
> goto err_disable_regulators;
> @@ -1548,6 +1553,7 @@ static const struct qcom_pcie_cfg sc7280_cfg = {
> .ops = &ops_1_9_0,
> .has_tbu_clk = true,
> .pipe_clk_need_muxing = true,
> + .suspend_poweroff = true,
> };
>
> static const struct dw_pcie_ops dw_pcie_ops = {
> --
> 2.25.1
>