2 * Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
4 * SPDX-License-Identifier: GPL-2.0+
12 #include <asm/arch/device.h>
13 #include <asm/arch/tnc.h>
14 #include <asm/fsp/fsp_support.h>
15 #include <asm/processor.h>
17 static int __maybe_unused disable_igd(void)
20 * According to Atom E6xx datasheet, setting VGA Disable (bit17)
21 * of Graphics Controller register (offset 0x50) prevents IGD
22 * (D2:F0) from reporting itself as a VGA display controller
23 * class in the PCI configuration space, and should also prevent
24 * it from responding to VGA legacy memory range and I/O addresses.
26 * However test result shows that with just VGA Disable bit set and
27 * a PCIe graphics card connected to one of the PCIe controllers on
28 * the E6xx, accessing the VGA legacy space still causes system hang.
29 * After a number of attempts, it turns out besides VGA Disable bit,
30 * the SDVO (D3:F0) device should be disabled to make it work.
32 * To simplify, use the Function Disable register (offset 0xc4)
33 * to disable both IGD (D2:F0) and SDVO (D3:F0) devices. Now these
34 * two devices will be completely disabled (invisible in the PCI
35 * configuration space) unless a system reset is performed.
37 x86_pci_write_config32(TNC_IGD, IGD_FD, FUNC_DISABLE);
38 x86_pci_write_config32(TNC_SDVO, IGD_FD, FUNC_DISABLE);
43 int arch_cpu_init(void)
47 post_code(POST_CPU_INIT);
49 ret = x86_cpu_init_f();
56 int arch_early_init_r(void)
60 #ifdef CONFIG_DISABLE_IGD