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With recent DM PCI changes to vesa_fb driver, external graphics card does not work any more. This is because: 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() used in the vesa_fb driver, 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. To fix this, manually remove these two devices. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Simon Glass <sjg@chromium.org> Tested-by: Simon Glass <sjg@chromium.org>
117 lines
3.3 KiB
C
117 lines
3.3 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 <dm.h>
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#include <dm/device-internal.h>
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#include <pci.h>
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#include <asm/io.h>
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#include <asm/irq.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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struct udevice *igd, *sdvo;
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int ret;
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ret = dm_pci_bus_find_bdf(TNC_IGD, &igd);
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if (ret)
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return ret;
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if (!igd)
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return 0;
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ret = dm_pci_bus_find_bdf(TNC_SDVO, &sdvo);
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if (ret)
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return ret;
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if (!sdvo)
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return 0;
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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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dm_pci_write_config32(igd, IGD_FD, FUNC_DISABLE);
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dm_pci_write_config32(sdvo, IGD_FD, FUNC_DISABLE);
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/*
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* After setting the function disable bit, IGD and SDVO devices will
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* disappear in the PCI configuration space. This however creates an
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* inconsistent state from a driver model PCI controller point of view,
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* as these two PCI devices are still attached to its parent's child
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* device list as maintained by the driver model. Some driver model PCI
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* APIs like dm_pci_find_class(), are referring to the list to speed up
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* the finding process instead of re-enumerating the whole PCI bus, so
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* it gets the stale cached data which is wrong.
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*
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* Note x86 PCI enueration normally happens twice, in pre-relocation
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* phase and post-relocation. One option might be to call disable_igd()
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* in one of the pre-relocation initialization hooks so that it gets
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* disabled in the first round, and when it comes to the second round
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* driver model PCI will construct a correct list. Unfortunately this
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* does not work as Intel FSP is used on this platform to perform low
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* level initialization, and fsp_init_phase_pci() is called only once
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* in the post-relocation phase. If we disable IGD and SDVO devices,
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* fsp_init_phase_pci() simply hangs and never returns.
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*
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* So the only option we have is to manually remove these two devices.
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*/
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ret = device_remove(igd);
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if (ret)
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return ret;
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ret = device_unbind(igd);
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if (ret)
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return ret;
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ret = device_remove(sdvo);
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if (ret)
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return ret;
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ret = device_unbind(sdvo);
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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_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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