Re: [PATCH v3 3/3] phy: qcom-qmp-pcie: Add support for keeping refclk always on

Manivannan Sadhasivam
2023-12-01T06:09:48Z

On Mon, Nov 27, 2023 at 05:43:51PM +0530, Krishna chaitanya chundru 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.
>
> Some platforms with pcie switch fail to drive the clkreq signal to
> the host from the endpoints because of the switch board design.
> Due to that refclk needs to supplied to the endpoint always.
>
> Add a flag to keep refclk always supplied to endpoint.
>
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
> 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 7fdf9b2596b6..e95f677817f7 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");

"Firmware requested to keep REFCLK always ON, but driver missing offset\n"

- Mani

> + goto err_node_put;
> + }
> +
> ret = phy_pipe_clk_register(qmp, np);
> if (ret)
> goto err_node_put;
>
> --
> 2.42.0
>
>

--
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