linux-kernel - [PATCH 3/3] PCI: meson: Fix parsing the DBI register region

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Message-Id: <20251031-pci-meson-fix-v1-3-ed29ee5b54f9@oss.qualcomm.com>
Date: Fri, 31 Oct 2025 23:13:01 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>, 
 Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Krzysztof Wilczyński <kwilczynski@...nel.org>, 
 Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Neil Armstrong <neil.armstrong@...aro.org>, 
 Hanjie Lin <hanjie.lin@...ogic.com>, Yue Wang <yue.wang@...ogic.com>, 
 Kevin Hilman <khilman@...libre.com>, Jerome Brunet <jbrunet@...libre.com>, 
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>, 
 Andrew Murray <amurray@...goodpenguin.co.uk>, 
 Jingoo Han <jingoohan1@...il.com>, 
 Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: linux-pci@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-amlogic@...ts.infradead.org, 
 Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>, 
 stable@...r.kernel.org, Linnaea Lavia <linnaea-von-lavia@...e.com>
Subject: [PATCH 3/3] PCI: meson: Fix parsing the DBI register region

First of all, the driver was parsing the 'dbi' register region as 'elbi'.
This was due to DT mistakenly passing 'dbi' as 'elbi'. Since the DT is
now fixed to supply 'dbi' region, this driver can rely on the DWC core
driver to parse and map it.

However, to support the old DTs, if the 'elbi' region is found in DT, parse
and map the region as both 'dw_pcie::elbi_base' as 'dw_pcie::dbi_base'.
This will allow the driver to work with both broken and fixed DTs.

Also, skip parsing the 'elbi' region in DWC core if 'pci->elbi_base' was
already populated.

Cc: <stable@...r.kernel.org> # 6.2
Reported-by: Linnaea Lavia <linnaea-von-lavia@...e.com>
Closes: https://lore.kernel.org/linux-pci/DM4PR05MB102707B8CDF84D776C39F22F2C7F0A@DM4PR05MB10270.namprd05.prod.outlook.com/
Fixes: 9c0ef6d34fdb ("PCI: amlogic: Add the Amlogic Meson PCIe controller driver")
Fixes: c96992a24bec ("PCI: dwc: Add support for ELBI resource mapping")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
---
 drivers/pci/controller/dwc/pci-meson.c       | 18 +++++++++++++++---
 drivers/pci/controller/dwc/pcie-designware.c | 12 +++++++-----
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
index 787469d1b396d4c7b3e28edfe276b7b997fb8aee..54b6a4196f1767a3c14c6c901bfee3505588134c 100644
--- a/drivers/pci/controller/dwc/pci-meson.c
+++ b/drivers/pci/controller/dwc/pci-meson.c
@@ -108,10 +108,22 @@ static int meson_pcie_get_mems(struct platform_device *pdev,
 			       struct meson_pcie *mp)
 {
 	struct dw_pcie *pci = &mp->pci;
+	struct resource *res;
 
-	pci->dbi_base = devm_platform_ioremap_resource_byname(pdev, "elbi");
-	if (IS_ERR(pci->dbi_base))
-		return PTR_ERR(pci->dbi_base);
+	/*
+	 * For the broken DTs that supply 'dbi' as 'elbi', parse the 'elbi'
+	 * region and assign it to both 'pci->elbi_base' and 'pci->dbi_space' so
+	 * that the DWC core can skip parsing both regions.
+	 */
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
+	if (res) {
+		pci->elbi_base = devm_pci_remap_cfg_resource(pci->dev, res);
+		if (IS_ERR(pci->elbi_base))
+			return PTR_ERR(pci->elbi_base);
+
+		pci->dbi_base = pci->elbi_base;
+		pci->dbi_phys_addr = res->start;
+	}
 
 	mp->cfg_base = devm_platform_ioremap_resource_byname(pdev, "cfg");
 	if (IS_ERR(mp->cfg_base))
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index c644216995f69cbf065e61a0392bf1e5e32cf56e..06eca858eb1b3c7a8a833df6616febcdbe854850 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -168,11 +168,13 @@ int dw_pcie_get_resources(struct dw_pcie *pci)
 	}
 
 	/* ELBI is an optional resource */
-	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
-	if (res) {
-		pci->elbi_base = devm_ioremap_resource(pci->dev, res);
-		if (IS_ERR(pci->elbi_base))
-			return PTR_ERR(pci->elbi_base);
+	if (!pci->elbi_base) {
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "elbi");
+		if (res) {
+			pci->elbi_base = devm_ioremap_resource(pci->dev, res);
+			if (IS_ERR(pci->elbi_base))
+				return PTR_ERR(pci->elbi_base);
+		}
 	}
 
 	/* LLDD is supposed to manually switch the clocks and resets state */

-- 
2.48.1