dm: pci: Allow disabling auto-config for a device

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>
This commit is contained in:
Simon Glass 2020-04-08 16:57:26 -06:00 committed by Bin Meng
parent 88307654af
commit d8c7fb5036
2 changed files with 25 additions and 0 deletions

View file

@ -10,6 +10,17 @@ Optional properties:
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 {
@ -21,4 +32,16 @@ pci {
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;
};
};

View file

@ -536,6 +536,8 @@ int pci_auto_config_devices(struct udevice *bus)
int ret;
debug("%s: device %s\n", __func__, dev->name);
if (dev_read_bool(dev, "pci,no-autoconfig"))
continue;
ret = dm_pciauto_config_device(dev);
if (ret < 0)
return ret;