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https://github.com/brain-hackers/u-boot-brain
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9e36c53dd0
So far disable_igd() does not have any return value, but we may need that in the future. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Simon Glass <sjg@chromium.org> Tested-by: Simon Glass <sjg@chromium.org>
66 lines
1.6 KiB
C
66 lines
1.6 KiB
C
/*
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* Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#include <asm/pci.h>
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#include <asm/post.h>
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#include <asm/arch/device.h>
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#include <asm/arch/tnc.h>
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#include <asm/fsp/fsp_support.h>
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#include <asm/processor.h>
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static int __maybe_unused disable_igd(void)
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{
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/*
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* According to Atom E6xx datasheet, setting VGA Disable (bit17)
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* of Graphics Controller register (offset 0x50) prevents IGD
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* (D2:F0) from reporting itself as a VGA display controller
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* class in the PCI configuration space, and should also prevent
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* it from responding to VGA legacy memory range and I/O addresses.
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*
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* However test result shows that with just VGA Disable bit set and
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* a PCIe graphics card connected to one of the PCIe controllers on
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* the E6xx, accessing the VGA legacy space still causes system hang.
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* After a number of attempts, it turns out besides VGA Disable bit,
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* the SDVO (D3:F0) device should be disabled to make it work.
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*
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* To simplify, use the Function Disable register (offset 0xc4)
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* to disable both IGD (D2:F0) and SDVO (D3:F0) devices. Now these
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* two devices will be completely disabled (invisible in the PCI
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* configuration space) unless a system reset is performed.
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*/
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x86_pci_write_config32(TNC_IGD, IGD_FD, FUNC_DISABLE);
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x86_pci_write_config32(TNC_SDVO, IGD_FD, FUNC_DISABLE);
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return 0;
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}
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int arch_cpu_init(void)
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{
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int ret;
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post_code(POST_CPU_INIT);
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ret = x86_cpu_init_f();
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if (ret)
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return ret;
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return 0;
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}
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int arch_early_init_r(void)
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{
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int ret = 0;
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#ifdef CONFIG_DISABLE_IGD
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ret = disable_igd();
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#endif
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return ret;
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}
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