PCI: aardvark: Disable link training when unbinding driver

Disable link training circuit in driver unbind sequence. We want to
leave link training in the same state as it was before the driver was
probed.

Link: https://lore.kernel.org/r/20211130172913.9727-11-kabel@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/pci-aardvark.c

@@ -1741,6 +1741,11 @@ static int advk_pcie_remove(struct platform_device *pdev)
 	if (pcie->reset_gpio)
 		gpiod_set_value_cansleep(pcie->reset_gpio, 1);
 
+	/* Disable link training */
+	val = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
+	val &= ~LINK_TRAINING_EN;
+	advk_writel(pcie, val, PCIE_CORE_CTRL0_REG);
+
 	/* Disable outbound address windows mapping */
 	for (i = 0; i < OB_WIN_COUNT; i++)
 		advk_pcie_disable_ob_win(pcie, i);