linux-kernel - [PATCH v2 13/14] PCI: brcmstb: Set bus max burst size by chip type

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Message-Id: <20200526191303.1492-14-james.quinlan@broadcom.com>
Date:   Tue, 26 May 2020 15:12:52 -0400
From:   Jim Quinlan <james.quinlan@...adcom.com>
To:     linux-pci@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        bcm-kernel-feedback-list@...adcom.com, james.quinlan@...adcom.com
Cc:     Jim Quinlan <james.quinlan@...adcom.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2 13/14] PCI: brcmstb: Set bus max burst size by chip type

From: Jim Quinlan <jquinlan@...adcom.com>

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 <jquinlan@...adcom.com>
---
 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 9930419e3ac2..131cf0a51398 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
@@ -848,7 +848,7 @@ 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);
@@ -864,10 +864,22 @@ 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 (pcie->type == BCM2711)
+		burst = 0x0; /* 128B */
+	else if (pcie->type == BCM7278)
+		burst = 0x3; /* 512 bytes */
+	else
+		burst = 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);
 
-- 
2.17.1