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/*
* Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <dm.h>
#include <dm/device-internal.h>
#include <pci.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/post.h>
#include <asm/arch/device.h>
#include <asm/arch/tnc.h>
#include <asm/fsp/fsp_support.h>
#include <asm/processor.h>
static int __maybe_unused disable_igd(void)
{
struct udevice *igd, *sdvo;
int ret;
ret = dm_pci_bus_find_bdf(TNC_IGD, &igd);
if (ret)
return ret;
if (!igd)
return 0;
ret = dm_pci_bus_find_bdf(TNC_SDVO, &sdvo);
if (ret)
return ret;
if (!sdvo)
return 0;
/*
* According to Atom E6xx datasheet, setting VGA Disable (bit17)
* of Graphics Controller register (offset 0x50) prevents IGD
* (D2:F0) from reporting itself as a VGA display controller
* class in the PCI configuration space, and should also prevent
* it from responding to VGA legacy memory range and I/O addresses.
*
* However test result shows that with just VGA Disable bit set and
* a PCIe graphics card connected to one of the PCIe controllers on
* the E6xx, accessing the VGA legacy space still causes system hang.
* After a number of attempts, it turns out besides VGA Disable bit,
* the SDVO (D3:F0) device should be disabled to make it work.
*
* To simplify, use the Function Disable register (offset 0xc4)
* to disable both IGD (D2:F0) and SDVO (D3:F0) devices. Now these
* two devices will be completely disabled (invisible in the PCI
* configuration space) unless a system reset is performed.
*/
dm_pci_write_config32(igd, IGD_FD, FUNC_DISABLE);
dm_pci_write_config32(sdvo, IGD_FD, FUNC_DISABLE);
/*
* After setting the function disable bit, IGD and SDVO devices will
* disappear in the PCI configuration space. This however creates an
* inconsistent state from a driver model PCI controller point of view,
* as these two PCI devices are still attached to its parent's child
* device list as maintained by the driver model. Some driver model PCI
* APIs like dm_pci_find_class(), are referring to the list to speed up
* the finding process instead of re-enumerating the whole PCI bus, so
* it gets the stale cached data which is wrong.
*
* Note x86 PCI enueration normally happens twice, in pre-relocation
* phase and post-relocation. One option might be to call disable_igd()
* in one of the pre-relocation initialization hooks so that it gets
* disabled in the first round, and when it comes to the second round
* driver model PCI will construct a correct list. Unfortunately this
* does not work as Intel FSP is used on this platform to perform low
* level initialization, and fsp_init_phase_pci() is called only once
* in the post-relocation phase. If we disable IGD and SDVO devices,
* fsp_init_phase_pci() simply hangs and never returns.
*
* So the only option we have is to manually remove these two devices.
*/
ret = device_remove(igd);
if (ret)
return ret;
ret = device_unbind(igd);
if (ret)
return ret;
ret = device_remove(sdvo);
if (ret)
return ret;
ret = device_unbind(sdvo);
if (ret)
return ret;
return 0;
}
int arch_cpu_init(void)
{
post_code(POST_CPU_INIT);
return x86_cpu_init_f();
}
int arch_early_init_r(void)
{
int ret = 0;
#ifdef CONFIG_DISABLE_IGD
ret = disable_igd();
#endif
return ret;
}
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