Commit cf68e3b7 authored by Vidya Sagar's avatar Vidya Sagar Committed by Lorenzo Pieralisi

PCI: tegra: Disable LTSSM during L2 entry

PCIe cards like Marvell SATA controller and some of the Samsung NVMe
drives don't support taking the link to L2 state. When the link doesn't
go to L2 state, Tegra194 requires the LTSSM to be disabled to allow PHY
to start the next link up process cleanly during suspend/resume sequence.
Failing to disable LTSSM results in the PCIe link not coming up in the
next resume cycle.

Link: https://lore.kernel.org/r/20201203133451.17716-6-vidyas@nvidia.comTested-by: default avatarThierry Reding <treding@nvidia.com>
Signed-off-by: default avatarVidya Sagar <vidyas@nvidia.com>
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: default avatarThierry Reding <treding@nvidia.com>
parent 3d710af7
......@@ -1506,6 +1506,14 @@ static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie)
data &= ~APPL_PINMUX_PEX_RST;
appl_writel(pcie, data, APPL_PINMUX);
/*
* Some cards do not go to detect state even after de-asserting
* PERST#. So, de-assert LTSSM to bring link to detect state.
*/
data = readl(pcie->appl_base + APPL_CTRL);
data &= ~APPL_CTRL_LTSSM_EN;
writel(data, pcie->appl_base + APPL_CTRL);
err = readl_poll_timeout_atomic(pcie->appl_base + APPL_DEBUG,
data,
((data &
......@@ -1513,14 +1521,8 @@ static void tegra_pcie_dw_pme_turnoff(struct tegra_pcie_dw *pcie)
APPL_DEBUG_LTSSM_STATE_SHIFT) ==
LTSSM_STATE_PRE_DETECT,
1, LTSSM_TIMEOUT);
if (err) {
if (err)
dev_info(pcie->dev, "Link didn't go to detect state\n");
} else {
/* Disable LTSSM after link is in detect state */
data = appl_readl(pcie, APPL_CTRL);
data &= ~APPL_CTRL_LTSSM_EN;
appl_writel(pcie, data, APPL_CTRL);
}
}
/*
* DBI registers may not be accessible after this as PLL-E would be
......
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