Re: [PATCH v2 3/3] PCI: qcom: Add rx margining settings for gen4

From: Manivannan Sadhasivam <mani@kernel.org>
To: Shashank Babu Chinta Venkata <quic_schintav@quicinc.com>
Cc: agross@kernel.org, andersson@kernel.org,
	konrad.dybcio@linaro.org, quic_msarkar@quicinc.com,
	quic_kraravin@quicinc.com,
	"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Rob Herring" <robh@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Jingoo Han" <jingoohan1@gmail.com>,
	"Gustavo Pimentel" <gustavo.pimentel@synopsys.com>,
	"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
	"Serge Semin" <fancer.lancer@gmail.com>,
	"Yoshihiro Shimoda" <yoshihiro.shimoda.uh@renesas.com>,
	"Conor Dooley" <conor.dooley@microchip.com>,
	linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v2 3/3] PCI: qcom: Add rx margining settings for gen4
Date: Tue, 2 Apr 2024 11:17:45 +0530	[thread overview]
Message-ID: <20240402054745.GK2933@thinkpad> (raw)
In-Reply-To: <20240320071527.13443-4-quic_schintav@quicinc.com>

On Wed, Mar 20, 2024 at 12:14:47AM -0700, Shashank Babu Chinta Venkata wrote:
> Add rx margining settings for gen4 operation.
> 

What is 'rx margining'? As mentioned in the previous patch, use 16 GT/s.

> Signed-off-by: Shashank Babu Chinta Venkata <quic_schintav@quicinc.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.h | 23 +++++++++++++
>  drivers/pci/controller/dwc/pcie-qcom-cmn.c   | 35 ++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-qcom-cmn.h   | 11 +++++-
>  drivers/pci/controller/dwc/pcie-qcom-ep.c    |  4 ++-
>  drivers/pci/controller/dwc/pcie-qcom.c       |  4 ++-
>  5 files changed, 74 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 064744bfe35a..ce1c5f9c406a 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -206,6 +206,29 @@
>  
>  #define PCIE_PL_CHK_REG_ERR_ADDR			0xB28
>  
> +/*
> + * GEN4 lane margining register definitions
> + */
> +#define GEN4_LANE_MARGINING_1_OFF		0xb80
> +#define MARGINING_MAX_VOLTAGE_OFFSET_MASK	GENMASK(29, 24)
> +#define MARGINING_NUM_VOLTAGE_STEPS_MASK	GENMASK(22, 16)
> +#define MARGINING_MAX_TIMING_OFFSET_MASK	GENMASK(13, 8)
> +#define MARGINING_NUM_TIMING_STEPS_MASK		GENMASK(5, 0)
> +#define MARGINING_MAX_VOLTAGE_OFFSET_SHIFT	24
> +#define MARGINING_NUM_VOLTAGE_STEPS_SHIFT	16
> +#define MARGINING_MAX_TIMING_OFFSET_SHIFT	8
> +
> +#define GEN4_LANE_MARGINING_2_OFF		0xb84
> +#define MARGINING_IND_ERROR_SAMPLER		BIT(28)
> +#define MARGINING_SAMPLE_REPORTING_METHOD	BIT(27)
> +#define MARGINING_IND_LEFT_RIGHT_TIMING		BIT(26)
> +#define MARGINING_IND_UP_DOWN_VOLTAGE		BIT(25)
> +#define MARGINING_VOLTAGE_SUPPORTED		BIT(24)
> +#define MARGINING_MAXLANES_MASK			GENMASK(20, 16)
> +#define MARGINING_SAMPLE_RATE_TIMING_MASK	GENMASK(13, 8)
> +#define MARGINING_SAMPLE_RATE_VOLTAGE_MASK	GENMASK(5, 0)
> +#define MARGINING_MAXLANES_SHIFT		16
> +#define MARGINING_SAMPLE_RATE_TIMING_SHIFT	8

Add a newline

>  /*
>   * iATU Unroll-specific register definitions
>   * From 4.80 core version the address translation will be made by unroll
> diff --git a/drivers/pci/controller/dwc/pcie-qcom-cmn.c b/drivers/pci/controller/dwc/pcie-qcom-cmn.c
> index 208a55e8e9a1..bf6b27ee8327 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom-cmn.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom-cmn.c
> @@ -53,6 +53,41 @@ void qcom_pcie_cmn_set_16gt_eq_settings(struct dw_pcie *pci)
>  }
>  EXPORT_SYMBOL_GPL(qcom_pcie_cmn_set_16gt_eq_settings);
>  
> +void qcom_pcie_cmn_set_16gt_rx_margining_settings(struct dw_pcie *pci)
> +{
> +	u32 reg;
> +
> +	reg = dw_pcie_readl_dbi(pci, GEN4_LANE_MARGINING_1_OFF);
> +	reg &= ~MARGINING_MAX_VOLTAGE_OFFSET_MASK;
> +	reg |= (MARGINING_MAX_VOLTAGE_OFFSET_VAL <<
> +		MARGINING_MAX_VOLTAGE_OFFSET_SHIFT);

Same comment as previous patch to use FIELD_* macros.

- Mani

-- 
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