[PATCH v3 07/29] dm: pci: Allow disabling auto-config for a device

Simon Glass
2020-03-30T23:12:43Z

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>
---

Changes in v3:
- Drop acpi,name in example

Changes in v2: None

doc/device-tree-bindings/pci/x86-pci.txt | 23 +++++++++++++++++++++++
drivers/pci/pci-uclass.c | 2 ++
2 files changed, 25 insertions(+)

diff --git a/doc/device-tree-bindings/pci/x86-pci.txt b/doc/device-tree-bindings/pci/x86-pci.txt
index 3aa5bd9a46c..95e370b3e72 100644
--- a/doc/device-tree-bindings/pci/x86-pci.txt
+++ b/doc/device-tree-bindings/pci/x86-pci.txt
@@ -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 at 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;
+ };
};
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index e2882e3b634..ceb64517047 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -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;
--
2.26.0.rc2.310.g2932bb562d-goog