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arm: a37xx: pci: Disable bus mastering when unloading driver

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Disable Root Bridge I/O space, memory space and bus mastering in Aardvark's
remove method, which is called before booting Linux kernel.

This ensures that PCIe device which was initialized and used by U-Boot
cannot do new DMA transfers until Linux initializes PCI subsystem and loads
appropriate drivers for the device.

During initialization of PCI subsystem Linux in fact disables this bus
mastering on Root Bridge (and later enables it when driver is loaded and
configured), but there is a possibility of a small window after U-Boot
boots Linux when bus mastering is enabled, which is not correct.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
This commit is contained in:
Pali Rohár 2021-05-26 17:59:35 +02:00 committed by Stefan Roese
parent 127dbec39a
commit 7b85aefd4b
1 changed files with 6 additions and 0 deletions
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6
drivers/pci/pci-aardvark.c
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@ -675,6 +675,12 @@ static int pcie_advk_remove(struct udevice *dev)
struct pcie_advk *pcie = dev_get_priv(dev);
u32 reg;
reg = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG);
reg &= ~(PCIE_CORE_CMD_MEM_ACCESS_EN |
PCIE_CORE_CMD_IO_ACCESS_EN |
PCIE_CORE_CMD_MEM_IO_REQ_EN);
advk_writel(pcie, reg, PCIE_CORE_CMD_STATUS_REG);
reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
reg &= ~LINK_TRAINING_EN;
advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);