Subject: Re: [PATCH 14/15] PCI: brcmstb: Set bus max burst side by chip type

From: Nicolas Saenz Julienne <[email-masked]>
Date: Wed, 20 May 2020 15:44:16 +0200

On Tue, 2020-05-19 at 16:34 -0400, Jim Quinlan wrote:
> From: Jim Quinlan <[email-masked]>
> 
> The proper value of the parameter SCB_MAX_BURST_SIZE varies
> per chip.  The 2711 family requires 128B whereas other devices
> can employ 512.  The assignment is complicated by the fact
> that the values for this two-bit field have different meanings;
> 
>   Value   Type_Generic    Type_7278
> 
>      00       Reserved         128B
>      01           128B         256B
>      10           256B         512B
>      11           512B     Reserved
> 
> Signed-off-by: Jim Quinlan <[email-masked]>
> ---
>  drivers/pci/controller/pcie-brcmstb.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c
> b/drivers/pci/controller/pcie-brcmstb.c
> index 7bf945efd71b..0dfa1bbd9764 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -53,7 +53,7 @@
>  #define  PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK		0x1000
>  #define  PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK	0x2000
>  #define  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK	0x300000
> -#define  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_128		0x0
> +
>  #define  PCIE_MISC_MISC_CTRL_SCB0_SIZE_MASK		0xf8000000
>  #define  PCIE_MISC_MISC_CTRL_SCB1_SIZE_MASK		0x07c00000
>  #define  PCIE_MISC_MISC_CTRL_SCB2_SIZE_MASK		0x0000001f
> @@ -276,6 +276,7 @@ struct brcm_pcie {
>  	int			num_memc;
>  	u64			memc_size[PCIE_BRCM_MAX_MEMC];
>  	u32			hw_rev;
> +	const struct of_device_id *of_id;
>  };
>  
>  /*
> @@ -841,7 +842,7 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
>  	int num_out_wins = 0;
>  	u16 nlw, cls, lnksta;
>  	int i, ret, memc;
> -	u32 tmp, aspm_support;
> +	u32 tmp, burst, aspm_support;
>  
>  	/* Reset the bridge */
>  	brcm_pcie_bridge_sw_init_set(pcie, 1);
> @@ -857,10 +858,20 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
>  	/* Wait for SerDes to be stable */
>  	usleep_range(100, 200);
>  
> +	/*
> +	 * SCB_MAX_BURST_SIZE is a two bit field.  For GENERIC chips it
> +	 * is encoded as 0=128, 1=256, 2=512, 3=Rsvd, for BCM7278 it
> +	 * is encoded as 0=Rsvd, 1=128, 2=256, 3=512.
> +	 */
> +	if (strcmp(pcie->of_id->compatible, "brcm,bcm2711-pcie") == 0)

Would it make sense to use pcie->type here? I know GENERIC != BCM2711, but we
could define it and avoid adding redundant info in struct brcm_pcie.

Regards,
Nicolas

> +		burst = 0x0; /* 128B */
> +	else
> +		burst = (pcie->type == BCM7278) ? 0x3 : 0x2; /* 512 bytes */
> +
>  	/* Set SCB_MAX_BURST_SIZE, CFG_READ_UR_MODE, SCB_ACCESS_EN */
>  	u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK);
>  	u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK);
> -	u32p_replace_bits(&tmp, PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_128,
> +	u32p_replace_bits(&tmp, burst,
>  			  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK);
>  	writel(tmp, base + PCIE_MISC_MISC_CTRL);
>  
> @@ -1200,6 +1211,7 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>  	pcie->reg_offsets = data->offsets;
>  	pcie->reg_field_info = data->reg_field_info;
>  	pcie->type = data->type;
> +	pcie->of_id = of_id;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	pcie->base = devm_ioremap_resource(&pdev->dev, res);

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