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

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Cc: Andy Gross <agross@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Vinod Koul <vkoul@kernel.org>,
	Kishon Vijay Abraham I <kishon@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	quic_vbadigan@quicinc.com, quic_ramkri@quicinc.com,
	quic_nitegupt@quicinc.com, quic_skananth@quicinc.com,
	quic_vpernami@quicinc.com, quic_parass@quicinc.com,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Subject: Re: [PATCH v3 3/3] phy: qcom-qmp-pcie: Add support for keeping refclk always on
Date: Fri, 1 Dec 2023 11:39:28 +0530	[thread overview]
Message-ID: <20231201060928.GK4009@thinkpad> (raw)
In-Reply-To: <20231127-refclk_always_on-v3-3-26d969fa8f1d@quicinc.com>

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
> 
> 

-- 
மணிவண்ணன் சதாசிவம்