linux-kernel - Re: [PATCH v5 4/4] PCI: qcom: Switch pcie_1_pipe_clk

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Date:   Tue, 17 Aug 2021 22:56:47 +0530
From:   Prasad Malisetty <pmaliset@...eaurora.org>
To:     agross@...nel.org, bjorn.andersson@...aro.org, bhelgaas@...gle.com,
        robh+dt@...nel.org, swboyd@...omium.org, lorenzo.pieralisi@....com,
        svarbanov@...sol.com
Cc:     devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        dianders@...omium.org, mka@...omium.org, vbadigan@...eaurora.org,
        sallenki@...eaurora.org, manivannan.sadhasivam@...aro.org
Subject: Re: [PATCH v5 4/4] PCI: qcom: Switch pcie_1_pipe_clk_src after PHY
 init in SC7280

On 2021-08-10 09:38, Prasad Malisetty wrote:
> On the SC7280, By default the clock source for pcie_1_pipe is
> TCXO for gdsc enable. But after the PHY is initialized, the clock
> source must be switched to gcc_pcie_1_pipe_clk from TCXO.
> 
> Signed-off-by: Prasad Malisetty <pmaliset@...eaurora.org>
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c
> b/drivers/pci/controller/dwc/pcie-qcom.c
> index 8a7a300..39e3b21 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -166,6 +166,8 @@ struct qcom_pcie_resources_2_7_0 {
>  	struct regulator_bulk_data supplies[2];
>  	struct reset_control *pci_reset;
>  	struct clk *pipe_clk;
> +	struct clk *gcc_pcie_1_pipe_clk_src;
> +	struct clk *phy_pipe_clk;
>  };
> 
>  union qcom_pcie_resources {
> @@ -1167,6 +1169,16 @@ static int qcom_pcie_get_resources_2_7_0(struct
> qcom_pcie *pcie)
>  	if (ret < 0)
>  		return ret;
> 
> +	if (of_device_is_compatible(dev->of_node, "qcom,pcie-sc7280")) {
> +		res->gcc_pcie_1_pipe_clk_src = devm_clk_get(dev, "pipe_mux");
> +		if (IS_ERR(res->gcc_pcie_1_pipe_clk_src))
> +			return PTR_ERR(res->gcc_pcie_1_pipe_clk_src);
> +
> +		res->phy_pipe_clk = devm_clk_get(dev, "phy_pipe");
> +		if (IS_ERR(res->phy_pipe_clk))
> +			return PTR_ERR(res->phy_pipe_clk);
> +	}
> +

Hi All,

Greetings!

I would like to check is there any other better approach instead of 
compatible method here as well or is it fine to use compatible method.

Thanks
-Prasad

>  	res->pipe_clk = devm_clk_get(dev, "pipe");
>  	return PTR_ERR_OR_ZERO(res->pipe_clk);
>  }
> @@ -1255,6 +1267,12 @@ static void qcom_pcie_deinit_2_7_0(struct
> qcom_pcie *pcie)
>  static int qcom_pcie_post_init_2_7_0(struct qcom_pcie *pcie)
>  {
>  	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
> +	struct dw_pcie *pci = pcie->pci;
> +	struct device *dev = pci->dev;
> +	struct device_node *node = dev->of_node;
> +
> +	if (of_property_read_bool(node, "pipe-clk-source-switch"))
> +		clk_set_parent(res->gcc_pcie_1_pipe_clk_src, res->phy_pipe_clk);
> 
>  	return clk_prepare_enable(res->pipe_clk);
>  }