linux-kernel - [PATCH 11/11] PCI: tegra194: Rework {start/stop}

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Message-Id: <20240314-pci-epf-rework-v1-11-6134e6c1d491@linaro.org>
Date: Thu, 14 Mar 2024 20:53:50 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Krzysztof Wilczyński <kw@...ux.com>, 
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Thierry Reding <thierry.reding@...il.com>, 
 Jonathan Hunter <jonathanh@...dia.com>, Jingoo Han <jingoohan1@...il.com>, 
 Gustavo Pimentel <gustavo.pimentel@...opsys.com>
Cc: linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, mhi@...ts.linux.dev, 
 linux-tegra@...r.kernel.org, 
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 Vidya Sagar <vidyas@...dia.com>
Subject: [PATCH 11/11] PCI: tegra194: Rework {start/stop}_link() callbacks
 implementation

DWC specific start_link() and stop_link() callbacks are supposed to start
and stop the link training of the PCIe bus. But the current endpoint
implementation of this driver enables/disables the PERST# IRQ.

Even though this is not causing any issues, this creates inconsistency
among the EP controller drivers. So for the sake of consistency, let's just
start/stop the link training in these callbacks.

Also, PERST# IRQ is now enabled from the start itself, thus allowing the
controller driver to initialize the registers when PERST# gets deasserted
without waiting for the user intervention though configfs.

Cc: Vidya Sagar <vidyas@...dia.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 3e6e08b321fb..03d6f248bc6f 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -964,7 +964,11 @@ static int tegra_pcie_dw_start_link(struct dw_pcie *pci)
 	bool retry = true;
 
 	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
-		enable_irq(pcie->pex_rst_irq);
+		/* Enable LTSSM */
+		val = appl_readl(pcie, APPL_CTRL);
+		val |= APPL_CTRL_LTSSM_EN;
+		appl_writel(pcie, val, APPL_CTRL);
+
 		return 0;
 	}
 
@@ -1049,8 +1053,12 @@ static int tegra_pcie_dw_link_up(struct dw_pcie *pci)
 static void tegra_pcie_dw_stop_link(struct dw_pcie *pci)
 {
 	struct tegra_pcie_dw *pcie = to_tegra_pcie(pci);
+	u32 val;
 
-	disable_irq(pcie->pex_rst_irq);
+	/* Disable LTSSM */
+	val = appl_readl(pcie, APPL_CTRL);
+	val &= ~APPL_CTRL_LTSSM_EN;
+	appl_writel(pcie, val, APPL_CTRL);
 }
 
 static const struct dw_pcie_ops tegra_dw_pcie_ops = {
@@ -1702,11 +1710,6 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie)
 	if (pcie->ep_state == EP_STATE_DISABLED)
 		return;
 
-	/* Disable LTSSM */
-	val = appl_readl(pcie, APPL_CTRL);
-	val &= ~APPL_CTRL_LTSSM_EN;
-	appl_writel(pcie, val, APPL_CTRL);
-
 	ret = readl_poll_timeout(pcie->appl_base + APPL_DEBUG, val,
 				 ((val & APPL_DEBUG_LTSSM_STATE_MASK) >>
 				 APPL_DEBUG_LTSSM_STATE_SHIFT) ==
@@ -1913,11 +1916,6 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
 		appl_writel(pcie, val, APPL_LTR_MSG_2);
 	}
 
-	/* Enable LTSSM */
-	val = appl_readl(pcie, APPL_CTRL);
-	val |= APPL_CTRL_LTSSM_EN;
-	appl_writel(pcie, val, APPL_CTRL);
-
 	pcie->ep_state = EP_STATE_ENABLED;
 	dev_dbg(dev, "Initialization of endpoint is completed\n");
 
@@ -2060,8 +2058,6 @@ static int tegra_pcie_config_ep(struct tegra_pcie_dw *pcie,
 		return -ENOMEM;
 	}
 
-	irq_set_status_flags(pcie->pex_rst_irq, IRQ_NOAUTOEN);
-
 	pcie->ep_state = EP_STATE_DISABLED;
 
 	ret = devm_request_threaded_irq(dev, pcie->pex_rst_irq, NULL,

-- 
2.25.1