PCI: mediatek-gen3: Add 100 ms delay after link up

The MediaTek Gen3 PCIe host driver lacks the required 100 ms delay after
link training completes for speeds > 5.0 GT/s, as specified in PCIe r6.0
sec 6.6.1.

The driver already stores max_link_speed (from the device tree). After
mtk_pcie_startup_port() successfully brings up the link, call
pci_host_common_link_train_delay() to comply with the specification.

Signed-off-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260518004246.1384532-7-18255117159@163.com

Author: Hans Zhang

drivers/pci/controller/pcie-mediatek-gen3.c

@@ -30,6 +30,7 @@
 #include <linux/regmap.h>
 #include <linux/reset.h>
 
+#include "pci-host-common.h"
 #include "../pci.h"
 
 #define PCIE_BASE_CFG_REG		0x14
@@ -570,6 +571,8 @@ static int mtk_pcie_startup_port(struct mtk_gen3_pcie *pcie)
 		goto err_power_down_device;
 	}
 
+	pci_host_common_link_train_delay(pcie->max_link_speed);
+
 	return 0;
 
 err_power_down_device: