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From:   Vidya Sagar <vidyas@nvidia.com>
To:     <jingoohan1@gmail.com>, <gustavo.pimentel@synopsys.com>,
        <lpieralisi@kernel.org>, <robh@kernel.org>, <kw@linux.com>,
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        <kthota@nvidia.com>, <mmaddireddy@nvidia.com>, <vidyas@nvidia.com>,
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Subject: [PATCH V2 2/2] PCI: designware-ep: Disable PTM capabilities for EP mode
Date:   Mon, 26 Sep 2022 16:40:17 +0530
Message-ID: <20220926111017.12655-3-vidyas@nvidia.com>
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Dual mode DesignWare PCIe IP has PTM capability enabled (if supported) even
in the EP mode. The PCIe compliance for the EP mode expects PTM
capabilities (ROOT_CAPABLE, RES_CAPABLE, CLK_GRAN) be disabled.
Hence disable PTM for the EP mode.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Reviewed-by: Jingoo Han <jingoohan1@gmail.com>
---
V2:
* Addressed review comment from Jingoo Han
* Added "Reviewed-by: Jingoo Han <jingoohan1@gmail.com>"

 .../pci/controller/dwc/pcie-designware-ep.c    | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 095fb0291ec9..b88b6597194a 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -638,6 +638,7 @@ static int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 	struct dw_pcie_ep_func *ep_func;
 	struct device *dev = pci->dev;
 	struct pci_epc *epc = ep->epc;
+	unsigned int ptm_cap_base;
 	unsigned int offset;
 	unsigned int nbars;
 	u8 hdr_type;
@@ -690,6 +691,7 @@ static int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 	}
 
 	offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
+	ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM);
 
 	dw_pcie_dbi_ro_wr_en(pci);
 
@@ -702,6 +704,22 @@ static int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
 			dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
 	}
 
+	/*
+	 * PTM responder capability can be disabled only after disabling
+	 * PTM root capability.
+	 */
+	if (ptm_cap_base) {
+		dw_pcie_dbi_ro_wr_en(pci);
+		reg = dw_pcie_readl_dbi(pci, ptm_cap_base + PCI_PTM_CAP);
+		reg &= ~PCI_PTM_CAP_ROOT;
+		dw_pcie_writel_dbi(pci, ptm_cap_base + PCI_PTM_CAP, reg);
+
+		reg = dw_pcie_readl_dbi(pci, ptm_cap_base + PCI_PTM_CAP);
+		reg &= ~(PCI_PTM_CAP_RES | PCI_PTM_GRANULARITY_MASK);
+		dw_pcie_writel_dbi(pci, ptm_cap_base + PCI_PTM_CAP, reg);
+		dw_pcie_dbi_ro_wr_dis(pci);
+	}
+
 	dw_pcie_setup(pci);
 	dw_pcie_dbi_ro_wr_dis(pci);
 
-- 
2.17.1