linux-kernel - Re: [PATCH v7 3/5] PCI: j721e: Add PCIe 4x lane selection support

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Date:   Fri, 25 Nov 2022 14:31:11 +0200
From:   Roger Quadros <rogerq@...nel.org>
To:     Matt Ranostay <mranostay@...com>, lpieralisi@...nel.org,
        robh@...nel.org, kw@...ux.com, bhelgaas@...gle.com,
        krzysztof.kozlowski@...aro.org, vigneshr@...com,
        tjoseph@...ence.com, sergio.paracuellos@...il.com,
        pthombar@...ence.com, linux-pci@...r.kernel.org
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 3/5] PCI: j721e: Add PCIe 4x lane selection support



On 24/11/2022 10:12, Matt Ranostay wrote:
> Add support for setting of two-bit field that allows selection of 4x lane
> PCIe which was previously limited to only 2x lanes.
> 
> Signed-off-by: Matt Ranostay <mranostay@...com>
> Reviewed-by: Vignesh Raghavendra <vigneshr@...com>
> ---
>  drivers/pci/controller/cadence/pci-j721e.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
> index 8990f58d64d5..dab3db9be6d8 100644
> --- a/drivers/pci/controller/cadence/pci-j721e.c
> +++ b/drivers/pci/controller/cadence/pci-j721e.c
> @@ -42,7 +42,6 @@ enum link_status {
>  };
>  
>  #define J721E_MODE_RC			BIT(7)
> -#define LANE_COUNT_MASK			BIT(8)
>  #define LANE_COUNT(n)			((n) << 8)
>  
>  #define GENERATION_SEL_MASK		GENMASK(1, 0)
> @@ -52,6 +51,7 @@ struct j721e_pcie {
>  	struct clk		*refclk;
>  	u32			mode;
>  	u32			num_lanes;
> +	u32			max_lanes;
>  	void __iomem		*user_cfg_base;
>  	void __iomem		*intd_cfg_base;
>  	u32			linkdown_irq_regfield;
> @@ -205,11 +205,15 @@ static int j721e_pcie_set_lane_count(struct j721e_pcie *pcie,
>  {
>  	struct device *dev = pcie->cdns_pcie->dev;
>  	u32 lanes = pcie->num_lanes;
> +	u32 mask = GENMASK(8, 8);

u32 mask = BIT(8);

>  	u32 val = 0;
>  	int ret;
>  
> +	if (pcie->max_lanes == 4)
> +		mask = GENMASK(9, 8);
> +
>  	val = LANE_COUNT(lanes - 1);
> -	ret = regmap_update_bits(syscon, offset, LANE_COUNT_MASK, val);
> +	ret = regmap_update_bits(syscon, offset, mask, val);
>  	if (ret)
>  		dev_err(dev, "failed to set link count\n");
>  
> @@ -439,6 +443,8 @@ static int j721e_pcie_probe(struct platform_device *pdev)
>  	ret = of_property_read_u32(node, "num-lanes", &num_lanes);
>  	if (ret || num_lanes > data->max_lanes)
>  		num_lanes = 1;
> +
> +	pcie->max_lanes = data->max_lanes;
>  	pcie->num_lanes = num_lanes;
>  
>  	if (dma_set_mask_and_coherent(dev, DMA_BIT_MASK(48)))

Reviewed-by: Roger Quadros <rogerq@...nel.org>

cheers,
-roger