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From:   Thippeswamy Havalige <thippeswamy.havalige@amd.com>
To:     <linux-kernel@vger.kernel.org>, <robh+dt@kernel.org>,
        <bhelgaas@google.com>, <krzysztof.kozlowski@linaro.org>,
        <linux-pci@vger.kernel.org>, <devicetree@vger.kernel.org>
CC:     <lpieralisi@kernel.org>, <bharat.kumar.gogada@amd.com>,
        <michal.simek@amd.com>, <linux-arm-kernel@lists.infradead.org>,
        "Thippeswamy Havalige" <thippeswamy.havalige@amd.com>
Subject: [PATCH v1 1/2] PCI: xilinx-nwl: Update ECAM default value and remove unnecessary code.
Date:   Mon, 7 Aug 2023 16:37:32 +0530
Message-ID: <20230807110733.77364-2-thippeswamy.havalige@amd.com>
In-Reply-To: <20230807110733.77364-1-thippeswamy.havalige@amd.com>
References: <20230807110733.77364-1-thippeswamy.havalige@amd.com>
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Our controller is expecting ECAM size to be programmed by software.
By programming "NWL_ECAM_VALUE_DEFAULT  12" controller can access up to
16MB ECAM region which is used to detect 16 buses, so by updating
"NWL_ECAM_VALUE_DEFAULT " to 16 so that controller can access up to 256MB
ECAM region to detect 256 buses.

E_ECAM_CONTROL register from bit 16 to 20 uses this value as input
to calculate ECAM Size.

The primary,secondary and sub-ordinate bus number registers are updated
by Linux PCI core, so removing code which is updating primary,secondary
and sub-ordinate bus numbers of type 1 header 18th offset of ECAM.

Signed-off-by: Thippeswamy Havalige <thippeswamy.havalige@amd.com>
Signed-off-by: Bharat Kumar Gogada <bharat.kumar.gogada@amd.com>
---
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: 
| https://lore.kernel.org/oe-kbuild-all/202308040330.eMTjX3tF-lkp@intel.
| com/
---
 drivers/pci/controller/pcie-xilinx-nwl.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/controller/pcie-xilinx-nwl.c b/drivers/pci/controller/pcie-xilinx-nwl.c
index 176686b..b515019 100644
--- a/drivers/pci/controller/pcie-xilinx-nwl.c
+++ b/drivers/pci/controller/pcie-xilinx-nwl.c
@@ -126,7 +126,7 @@
 #define E_ECAM_CR_ENABLE		BIT(0)
 #define E_ECAM_SIZE_LOC			GENMASK(20, 16)
 #define E_ECAM_SIZE_SHIFT		16
-#define NWL_ECAM_VALUE_DEFAULT		12
+#define NWL_ECAM_VALUE_DEFAULT		16
 
 #define CFG_DMA_REG_BAR			GENMASK(2, 0)
 #define CFG_PCIE_CACHE			GENMASK(7, 0)
@@ -165,8 +165,6 @@ struct nwl_pcie {
 	u32 ecam_size;
 	int irq_intx;
 	int irq_misc;
-	u32 ecam_value;
-	u8 last_busno;
 	struct nwl_msi msi;
 	struct irq_domain *legacy_irq_domain;
 	struct clk *clk;
@@ -625,7 +623,7 @@ static int nwl_pcie_bridge_init(struct nwl_pcie *pcie)
 {
 	struct device *dev = pcie->dev;
 	struct platform_device *pdev = to_platform_device(dev);
-	u32 breg_val, ecam_val, first_busno = 0;
+	u32 breg_val, ecam_val;
 	int err;
 
 	breg_val = nwl_bridge_readl(pcie, E_BREG_CAPABILITIES) & BREG_PRESENT;
@@ -675,7 +673,7 @@ static int nwl_pcie_bridge_init(struct nwl_pcie *pcie)
 			  E_ECAM_CR_ENABLE, E_ECAM_CONTROL);
 
 	nwl_bridge_writel(pcie, nwl_bridge_readl(pcie, E_ECAM_CONTROL) |
-			  (pcie->ecam_value << E_ECAM_SIZE_SHIFT),
+			  (NWL_ECAM_VALUE_DEFAULT << E_ECAM_SIZE_SHIFT),
 			  E_ECAM_CONTROL);
 
 	nwl_bridge_writel(pcie, lower_32_bits(pcie->phys_ecam_base),
@@ -683,15 +681,6 @@ static int nwl_pcie_bridge_init(struct nwl_pcie *pcie)
 	nwl_bridge_writel(pcie, upper_32_bits(pcie->phys_ecam_base),
 			  E_ECAM_BASE_HI);
 
-	/* Get bus range */
-	ecam_val = nwl_bridge_readl(pcie, E_ECAM_CONTROL);
-	pcie->last_busno = (ecam_val & E_ECAM_SIZE_LOC) >> E_ECAM_SIZE_SHIFT;
-	/* Write primary, secondary and subordinate bus numbers */
-	ecam_val = first_busno;
-	ecam_val |= (first_busno + 1) << 8;
-	ecam_val |= (pcie->last_busno << E_ECAM_SIZE_SHIFT);
-	writel(ecam_val, (pcie->ecam_base + PCI_PRIMARY_BUS));
-
 	if (nwl_pcie_link_up(pcie))
 		dev_info(dev, "Link is UP\n");
 	else
@@ -792,7 +781,6 @@ static int nwl_pcie_probe(struct platform_device *pdev)
 	pcie = pci_host_bridge_priv(bridge);
 
 	pcie->dev = dev;
-	pcie->ecam_value = NWL_ECAM_VALUE_DEFAULT;
 
 	err = nwl_pcie_parse_dt(pcie, pdev);
 	if (err) {
-- 
1.8.3.1