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https://github.com/brain-hackers/u-boot-brain
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d8c7fb5036
Add a means to avoid configuring a device when needed. Add an explanation of why this is useful to the binding file. Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
48 lines
1.5 KiB
Plaintext
48 lines
1.5 KiB
Plaintext
x86 PCI DT details:
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===================
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Some options are available to affect how PCI operates on x86.
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Optional properties:
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- u-boot,skip-auto-config-until-reloc : Don't set up PCI configuration until
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after U-Boot has relocated. Normally if PCI is used before relocation,
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this happens before relocation also. Some platforms set up static
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configuration in TPL/SPL to reduce code size and boot time, since these
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phases only know about a small subset of PCI devices.
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For PCI devices the following optional property is available:
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- pci,no-autoconfig : Don't automatically configure this PCI device at all.
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This is used when the device is statically configured and must maintain
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this same config throughout the boot process. An example is a serial
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UART being used to debug PCI configuration, since reconfiguring it stops
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the UART from working until the driver is re-probed, and this can cause
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output to be lost. This should not generally be used in production code,
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although it is often harmless.
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Example:
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pci {
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compatible = "pci-x86";
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#address-cells = <3>;
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#size-cells = <2>;
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u-boot,dm-pre-reloc;
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ranges = <0x02000000 0x0 0xc0000000 0xc0000000 0 0x10000000
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0x42000000 0x0 0xb0000000 0xb0000000 0 0x10000000
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0x01000000 0x0 0x1000 0x1000 0 0xefff>;
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u-boot,skip-auto-config-until-reloc;
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serial: serial@18,2 {
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reg = <0x0200c210 0 0 0 0>;
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u-boot,dm-pre-reloc;
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compatible = "intel,apl-ns16550";
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early-regs = <0xde000000 0x20>;
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reg-shift = <2>;
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clock-frequency = <1843200>;
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current-speed = <115200>;
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pci,no-autoconfig;
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};
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};
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