linux-kernel - Re: [PATCH] PCI: qcom: add missing supplies required for msm8996

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Message-ID: <4fd5f3e7-73f6-ad63-c961-47f1f0fac149@mm-sol.com>
Date:   Thu, 14 Dec 2017 12:06:02 +0200
From:   Stanimir Varbanov <svarbanov@...sol.com>
To:     srinivas.kandagatla@...aro.org, stanimir.varbanov@...aro.org,
        linux-pci@...r.kernel.org, bhelgaas@...gle.com
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        Bjorn Helgaas <helgaas@...nel.org>
Subject: Re: [PATCH] PCI: qcom: add missing supplies required for msm8996

Hi Srini,

On 12/08/2017 11:20 AM, srinivas.kandagatla@...aro.org wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> 
> This patch adds supplies that are required for msm8996. Two of them vdda
> and vdda-1p8 are analog supplies that go in to controller, and the rest

According to the msm8996 device specification there are two pins related
to the PCIe power: VDD_PCIE_CORE (power for PCIe core circuitry) and
VDD_PCIE_1P8 (power for PCIe I/O circuitry). Thus I think it is clear
that VDD_PCIE_CORE is vdda and VDD_PCIE_1P8 should be part of PCIe phy
driver DT binding (and this is the case currently [1]). So I don't think
we need vdda-1p8 regulator DT binding for that in pcie-qcom.

> of the two vddpe's are supplies to PCIe endpoints.

For this part I'm still not sure. On first sight it looks that these
vdd's should be part of endpoint drivers, on the other hand we have
mPCIe connector (on db820c) which has two power rails 3p3v and 1p5v
which should be controlled/enabled as well.

So I'd like to hear more opinions on that, i.e. how this is solved by
the other PCIe bridge drivers.

> 
> Without these supplies PCIe endpoints which require power supplies are
> not enumerated at all, as there is no one to power it up.
> 
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> ---
>  .../devicetree/bindings/pci/qcom,pcie.txt          | 16 +++++++++++++
>  drivers/pci/dwc/pcie-qcom.c                        | 28 ++++++++++++++++++++--
>  2 files changed, 42 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pci/qcom,pcie.txt b/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> index 3c9d321b3d3b..045102cb3e12 100644
> --- a/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/qcom,pcie.txt
> @@ -179,6 +179,11 @@
>  	Value type: <phandle>
>  	Definition: A phandle to the core analog power supply
>  
> +- vdda-1p8-supply:
> +	Usage: required for msm8996
> +	Value type: <phandle>
> +	Definition: A phandle to the 1.8v analog power supply
> +
>  - vdda_phy-supply:
>  	Usage: required for ipq/apq8064
>  	Value type: <phandle>
> @@ -189,6 +194,15 @@
>  	Value type: <phandle>
>  	Definition: A phandle to the analog power supply for IC which generates
>  		    reference clock
> +- vddpe-supply:
> +	Usage: optional
> +	Value type: <phandle>
> +	Definition: A phandle to the PCIe endpoint power supply
> +
> +- vddpe1-supply:
> +	Usage: optional
> +	Value type: <phandle>
> +	Definition: A phandle to the PCIe endpoint power supply 1
>  
>  - phys:
>  	Usage: required for apq8084
> @@ -205,6 +219,8 @@
>  	Value type: <prop-encoded-array>
>  	Definition: List of phandle and GPIO specifier pairs. Should contain
>  			- "perst-gpios"	PCIe endpoint reset signal line
> +			- "pe_en-gpios"	PCIe endpoint enable signal line
> +			- "pe_en1-gpios" PCIe endpoint enable1 signal line

those two shouldn't be here, instead they should be part of regulator DT
node, so please drop them.

>  			- "wake-gpios"	PCIe endpoint wake signal line
>  
>  * Example for ipq/apq8064
> diff --git a/drivers/pci/dwc/pcie-qcom.c b/drivers/pci/dwc/pcie-qcom.c
> index 952a4fc4bf3c..01488f90da31 100644
> --- a/drivers/pci/dwc/pcie-qcom.c
> +++ b/drivers/pci/dwc/pcie-qcom.c
> @@ -109,13 +109,15 @@ struct qcom_pcie_resources_1_0_0 {
>  	struct reset_control *core;
>  	struct regulator *vdda;
>  };
> -
> +#define QCOM_PCIE_MAX_SUPPLY	4
>  struct qcom_pcie_resources_2_3_2 {
>  	struct clk *aux_clk;
>  	struct clk *master_clk;
>  	struct clk *slave_clk;
>  	struct clk *cfg_clk;
>  	struct clk *pipe_clk;
> +	int num_supplies;
> +	struct regulator_bulk_data supplies[QCOM_PCIE_MAX_SUPPLY];
>  };
>  
>  struct qcom_pcie_resources_2_4_0 {
> @@ -529,6 +531,17 @@ static int qcom_pcie_get_resources_2_3_2(struct qcom_pcie *pcie)
>  	struct qcom_pcie_resources_2_3_2 *res = &pcie->res.v2_3_2;
>  	struct dw_pcie *pci = pcie->pci;
>  	struct device *dev = pci->dev;
> +	int ret;
> +
> +	res->supplies[0].supply = "vdda";
> +	res->supplies[1].supply = "vdda-1p8";
> +	res->supplies[2].supply = "vddpe";
> +	res->supplies[3].supply = "vddpe1";
> +	res->num_supplies = QCOM_PCIE_MAX_SUPPLY;
> +	ret = devm_regulator_bulk_get(dev, QCOM_PCIE_MAX_SUPPLY,
> +				      res->supplies);

If we decide to go on this direction we need to replace this with
devm_regulator_bulk_get_optional (yes I know there is no such regulator
API yet) because they are optional in the DT binding.

<snip>

-- 
regards,
Stan

[1]
https://elixir.free-electrons.com/linux/latest/source/arch/arm64/boot/dts/qcom/msm8996.dtsi#L638