mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-07 21:54:45 +00:00
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>
47 lines
1.5 KiB
Text
47 lines
1.5 KiB
Text
x86 PCI DT details:
|
|
===================
|
|
|
|
Some options are available to affect how PCI operates on x86.
|
|
|
|
Optional properties:
|
|
- u-boot,skip-auto-config-until-reloc : Don't set up PCI configuration until
|
|
after U-Boot has relocated. Normally if PCI is used before relocation,
|
|
this happens before relocation also. Some platforms set up static
|
|
configuration in TPL/SPL to reduce code size and boot time, since these
|
|
phases only know about a small subset of PCI devices.
|
|
|
|
For PCI devices the following optional property is available:
|
|
|
|
- pci,no-autoconfig : Don't automatically configure this PCI device at all.
|
|
This is used when the device is statically configured and must maintain
|
|
this same config throughout the boot process. An example is a serial
|
|
UART being used to debug PCI configuration, since reconfiguring it stops
|
|
the UART from working until the driver is re-probed, and this can cause
|
|
output to be lost. This should not generally be used in production code,
|
|
although it is often harmless.
|
|
|
|
|
|
Example:
|
|
|
|
pci {
|
|
compatible = "pci-x86";
|
|
#address-cells = <3>;
|
|
#size-cells = <2>;
|
|
u-boot,dm-pre-reloc;
|
|
ranges = <0x02000000 0x0 0xc0000000 0xc0000000 0 0x10000000
|
|
0x42000000 0x0 0xb0000000 0xb0000000 0 0x10000000
|
|
0x01000000 0x0 0x1000 0x1000 0 0xefff>;
|
|
u-boot,skip-auto-config-until-reloc;
|
|
|
|
|
|
serial: serial@18,2 {
|
|
reg = <0x0200c210 0 0 0 0>;
|
|
u-boot,dm-pre-reloc;
|
|
compatible = "intel,apl-ns16550";
|
|
early-regs = <0xde000000 0x20>;
|
|
reg-shift = <2>;
|
|
clock-frequency = <1843200>;
|
|
current-speed = <115200>;
|
|
pci,no-autoconfig;
|
|
};
|
|
};
|