Re: [PATCH v2] PCI: qcom: Allow L1 and its sub states

From: Bjorn Helgaas
Date: Fri Jun 24 2022 - 13:11:18 EST


On Wed, Jun 15, 2022 at 06:45:39PM +0530, Krishna chaitanya chundru wrote:
> Allow L1 and its sub-states in the qcom pcie driver.
> By default this is disabled in the hardware. So enabling it explicitly.
>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>

I have a vague memory of my questions at [1] being answered, but I
don't see the answers on the mailing list. Maybe I missed it?

We should expand the commit log a bit with those details.

I'm also hoping for an ack from Stanimir, Andy, or Bjorn A., since
they're listed as maintainers of this driver.

[1] https://lore.kernel.org/r/20220615154422.GA941075@bhelgaas

> ---
> drivers/pci/controller/dwc/pcie-qcom.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 6ab9089..0d8efcc 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -41,6 +41,9 @@
> #define L23_CLK_RMV_DIS BIT(2)
> #define L1_CLK_RMV_DIS BIT(1)
>
> +#define PCIE20_PARF_PM_CTRL 0x20
> +#define REQ_NOT_ENTR_L1 BIT(5)
> +
> #define PCIE20_PARF_PHY_CTRL 0x40
> #define PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK GENMASK(20, 16)
> #define PHY_CTRL_PHY_TX0_TERM_OFFSET(x) ((x) << 16)
> @@ -1267,6 +1270,11 @@ static int qcom_pcie_init_2_7_0(struct qcom_pcie *pcie)
> val |= BIT(4);
> writel(val, pcie->parf + PCIE20_PARF_MHI_CLOCK_RESET_CTRL);
>
> + /* Enable L1 and L1ss */
> + val = readl(pcie->parf + PCIE20_PARF_PM_CTRL);
> + val &= ~REQ_NOT_ENTR_L1;
> + writel(val, pcie->parf + PCIE20_PARF_PM_CTRL);
> +
> if (IS_ENABLED(CONFIG_PCI_MSI)) {
> val = readl(pcie->parf + PCIE20_PARF_AXI_MSTR_WR_ADDR_HALT);
> val |= BIT(31);
> --
> 2.7.4
>