From: Furquan Shaikh <furquan@xxxxxxxxxx> Dear Linux folks, Google Chromebooks are often built with devices sourced from different vendors. These need to be probed. To deal with this, the firmware – in this case coreboot – tags such optional devices accordingly – I think this is commit fbf2c79b (drivers/i2c/generic: Add config for marking device as probed) – and Chromium OS’ Linux kernel has the patch at hand applied to act accordingly. Right after the merge, Dmitry created a revert, which was actively discussed for two days but wasn’t applied. That means, millions of devices shipped with such a firmware and Linux kernel. To support these devices with upstream Linux kernel, is there an alternative to applying the patch to the Linux kernel, and to support the shipped devices? Kind regards, Paul [1]: https://review.coreboot.org/c/coreboot/+/16742/ [2]: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1104997 --------------- 8< -------------------------- >8 --------------- Add a new device property to indicate if an I2C device should be probed before being added. If this property is present and set then the I2C core layer will use i2c_new_probed_device() instead of i2c_new_device(). This can be used to provide devices in ACPI or DT that may not be present on the board. For example, multiple trackpad vendors can be supported on a single board with a unified firmware image this way by having their device address be probed before being added. This property is styled after the PCI Host Bridge probe property (bindings/pci/host-generic-pci.txt:linuxk,pci-probe-only) and is a linux specific directive to alter device probing. BUG=b:110013532 TEST=tested on soraka with 4.14 kernel: 1) add "linux,probed=1" device property to the touchscreen ACPI device on soraka and ensure that the device is probed before being added. tested on yorp with 4.14 kernel: 1) I2C devices without the "linux,probed=1" device property are still functional. Original-change-Id: I9cf689f7b75ef445c1f0e9f7ec143fa695eb398e Original-signed-off-by: Duncan Laurie <dlaurie@xxxxxxxxxxxx> Original-reviewed-on: https://chromium-review.googlesource.com/388767 Original-reviewed-by: Benson Leung <bleung@xxxxxxxxxxxx> Change-Id: I54015fe102f2834f6a094d9e650c166a0cc0583b Signed-off-by: Furquan Shaikh <furquan@xxxxxxxxxx> Reviewed-on: https://chromium-review.googlesource.com/1100544 Commit-Ready: Furquan Shaikh <furquan@xxxxxxxxxxxx> Tested-by: Furquan Shaikh <furquan@xxxxxxxxxxxx> Reviewed-by: Justin TerAvest <teravest@xxxxxxxxxxxx> Conflicts: drivers/i2c/i2c-core-of.c [rebase419(groeck): Context conflicts] Signed-off-by: Guenter Roeck <groeck@xxxxxxxxxxxx> [rebase510(groeck): Context conflicts] Signed-off-by: Guenter Roeck <groeck@xxxxxxxxxxxx> Change-Id: Id10adae00b381e62813fd6b8ce7c6c50f140c31b --- Documentation/devicetree/bindings/i2c/i2c.txt | 5 +++++ drivers/i2c/i2c-core-acpi.c | 12 +++++++++++- drivers/i2c/i2c-core-of.c | 10 +++++++++- 3 files changed, 25 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt index b864916e087f..4921ee57f4c1 100644 --- a/Documentation/devicetree/bindings/i2c/i2c.txt +++ b/Documentation/devicetree/bindings/i2c/i2c.txt @@ -133,6 +133,11 @@ wants to support one of the below features, it should adapt these bindings. - wakeup-source device can be used as a wakeup source. +- linux,probed + If this property is present, then the I2C device will be + probed before being added using i2c_new_scanned_device, else + linux will instantiate the I2C device normally. + Binding may contain optional "interrupts" property, describing interrupts used by the device. I2C core will assign "irq" interrupt (or the very first interrupt if not using interrupt names) as primary interrupt for the slave. diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c index 92c1cc07ed46..c970d99e4438 100644 --- a/drivers/i2c/i2c-core-acpi.c +++ b/drivers/i2c/i2c-core-acpi.c @@ -254,10 +254,20 @@ static void i2c_acpi_register_device(struct i2c_adapter *adapter, struct acpi_device *adev, struct i2c_board_info *info) { + struct i2c_client *client; + adev->power.flags.ignore_parent = true; acpi_device_set_enumerated(adev); - if (IS_ERR(i2c_new_client_device(adapter, info))) + if (!acpi_dev_get_property(adev, "linux,probed", ACPI_TYPE_ANY, NULL)) { + unsigned short addrs[] = { info->addr, I2C_CLIENT_END }; + + client = i2c_new_scanned_device(adapter, info, addrs, NULL); + } else { + client = i2c_new_client_device(adapter, info); + } + + if (IS_ERR(client)) adev->power.flags.ignore_parent = false; } diff --git a/drivers/i2c/i2c-core-of.c b/drivers/i2c/i2c-core-of.c index 3ed74aa4b44b..fd375ce38a9e 100644 --- a/drivers/i2c/i2c-core-of.c +++ b/drivers/i2c/i2c-core-of.c @@ -75,7 +75,15 @@ static struct i2c_client *of_i2c_register_device(struct i2c_adapter *adap, if (ret) return ERR_PTR(ret); - client = i2c_new_client_device(adap, &info); + /* Allow device property to enable probing before init */ + if (of_get_property(node, "linux,probed", NULL)) { + unsigned short addrs[] = { info.addr, I2C_CLIENT_END }; + + client = i2c_new_scanned_device(adap, &info, addrs, NULL); + } else { + client = i2c_new_client_device(adap, &info); + } + if (IS_ERR(client)) dev_err(&adap->dev, "of_i2c: Failure registering %pOF\n", node); -- 2.34.1
