On Mon, Nov 06, 2023 at 05:22:35PM +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.
>
> If there is some issues in platform with clkreq signal propagation
> 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
Double <space> ------------^^
> states.
>
> Add a flag which indicates refclk is always supplied to endpoint.
>
The patch itself look good, the problem description looks good, but if
you have an indication that the refclk "is always supplied to the
endpoint", then you don't have a problem with refclk and I don't think
you need this patch.
Something to the tune of "keep refclk always supplied to endpoint" seems
to more appropriately describe what this flag is doing.
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> ---
> drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
> index a63ca7424974..d7e377a7d96e 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
>
> @@ -77,6 +79,7 @@ enum qphy_reg_layout {
> QPHY_START_CTRL,
> QPHY_PCS_STATUS,
> QPHY_PCS_POWER_DOWN_CONTROL,
> + QPHY_PCS_ENDPOINT_REFCLK_CNTRL,
> /* Keep last to ensure regs_layout arrays are properly initialized */
> QPHY_LAYOUT_SIZE
> };
> @@ -103,10 +106,11 @@ static const unsigned int sdm845_qhp_pciephy_regs_layout[QPHY_LAYOUT_SIZE] = {
> };
>
> static const unsigned int pciephy_v4_regs_layout[QPHY_LAYOUT_SIZE] = {
> - [QPHY_SW_RESET] = QPHY_V4_PCS_SW_RESET,
> - [QPHY_START_CTRL] = QPHY_V4_PCS_START_CONTROL,
> - [QPHY_PCS_STATUS] = QPHY_V4_PCS_PCS_STATUS1,
> - [QPHY_PCS_POWER_DOWN_CONTROL] = QPHY_V4_PCS_POWER_DOWN_CONTROL,
> + [QPHY_SW_RESET] = QPHY_V4_PCS_SW_RESET,
> + [QPHY_START_CTRL] = QPHY_V4_PCS_START_CONTROL,
> + [QPHY_PCS_STATUS] = QPHY_V4_PCS_PCS_STATUS1,
> + [QPHY_PCS_POWER_DOWN_CONTROL] = QPHY_V4_PCS_POWER_DOWN_CONTROL,
> + [QPHY_PCS_ENDPOINT_REFCLK_CNTRL] = QPHY_V4_PCS_PCIE_ENDPOINT_REFCLK_CNTRL,
> };
>
> static const unsigned int pciephy_v5_regs_layout[QPHY_LAYOUT_SIZE] = {
> @@ -2244,6 +2248,8 @@ struct qmp_pcie {
> struct phy *phy;
> int mode;
>
> + bool refclk_always_on;
> +
> struct clk_fixed_rate pipe_clk_fixed;
> };
>
> @@ -3159,6 +3165,10 @@ 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);
> @@ -3681,6 +3691,9 @@ 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");
Leave this line unwrapped, for readability.
Regards,
Bjorn
> +
> ret = phy_pipe_clk_register(qmp, np);
> if (ret)
> goto err_node_put;
>
> --
> 2.42.0
>
