On Tue, 7 Nov 2023 at 14:26, Krishna chaitanya chundru
<quic_krichai@xxxxxxxxxxx> wrote:
>
> In PCIe low power states like L1.1 or L1.2 the phy will stop
> supplying refclk to endpoint. If endpoint asserts clkreq to bring
> back link L0, then RC needs to provide refclk to endpoint.
>
> If there is some issues in platform with clkreq signal propagation
Nit: there are
I'd rephrase this in the following way:
Some platforms (e.g. ABC DEF) fail to drive the clkreq signal to the
host (because it is unconnected ?). Due to that...
Other than that:
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> to host and due to that host will not send refclk which results PCIe link
> down. For those platforms phy needs to provide refclk even in low power
> states.
>
> Add a flag to keep refclk always supplied to endpoint.
>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> ---
> drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> index 74d03d217ff2..a8d6d69e3f74 100644
> --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> @@ -43,6 +43,8 @@
> /* QPHY_PCS_STATUS bit */
> #define PHYSTATUS BIT(6)
> #define PHYSTATUS_4_20 BIT(7)
> +/* PCS_PCIE_ENDPOINT_REFCLK_CNTRL */
> +#define EPCLK_ALWAYS_ON_EN BIT(6)
>
> #define PHY_INIT_COMPLETE_TIMEOUT 10000
>
> @@ -2264,6 +2266,8 @@ struct qmp_pcie {
> struct phy *phy;
> int mode;
>
> + bool refclk_always_on;
> +
> struct clk_fixed_rate pipe_clk_fixed;
> };
>
> @@ -3179,6 +3183,10 @@ static void qmp_pcie_init_registers(struct qmp_pcie *qmp, const struct qmp_phy_c
> qmp_pcie_configure(pcs, tbls->pcs, tbls->pcs_num);
> qmp_pcie_configure(pcs_misc, tbls->pcs_misc, tbls->pcs_misc_num);
>
> + if (qmp->refclk_always_on && cfg->regs[QPHY_PCS_ENDPOINT_REFCLK_CNTRL])
> + qphy_setbits(pcs_misc, cfg->regs[QPHY_PCS_ENDPOINT_REFCLK_CNTRL],
> + EPCLK_ALWAYS_ON_EN);
> +
> if (cfg->lanes >= 4 && qmp->tcsr_4ln_config) {
> qmp_pcie_configure(serdes, cfg->serdes_4ln_tbl, cfg->serdes_4ln_num);
> qmp_pcie_init_port_b(qmp, tbls);
> @@ -3701,6 +3709,12 @@ static int qmp_pcie_probe(struct platform_device *pdev)
> if (ret)
> goto err_node_put;
>
> + qmp->refclk_always_on = of_property_read_bool(dev->of_node, "qcom,refclk-always-on");
> + if (qmp->refclk_always_on && !qmp->cfg->regs[QPHY_PCS_ENDPOINT_REFCLK_CNTRL]) {
> + dev_err(dev, "refclk is always on is present but refclk cntrl offset is not present\n");
> + goto err_node_put;
> + }
> +
> ret = phy_pipe_clk_register(qmp, np);
> if (ret)
> goto err_node_put;
>
> --
> 2.42.0
>
>
--
With best wishes
Dmitry
