Messages in this thread Patch in this message | | | From | Frans Klaver <> | Subject | [PATCH] sbs-battery: add option to always register battery | Date | Tue, 2 Jun 2015 15:14:43 +0200 |
| |
Commit a22b41a31e53 ("sbs-battery: Probe should try talking to the device") introduced a step in probing the SBS battery, that tries to talk to the device before actually registering it, saying:
this driver doesn't actually try talking to the device at probe time, so if it's incorrectly configured in the device tree or platform data (or if the battery has been removed from the system), then probe will succeed and every access will sit there and time out. The end result is a possibly laggy system that thinks it has a battery but can never read status, which isn't very useful.
Which is of course reasonable. However, it is also very well possible for a device to boot up on wall-power and be connected to a battery later on. The current advice in this situation is to probe the device from userspace if you expect the battery to come on at some point in the future. The downside of this approach is that userspace needs to be aware of the backend of its powersupply, which is inconvenient and going against the point of hardware abstraction.
In some of these cases you do want to register a battery, even if none are attached at the moment. To facilitate this, add a configuration option to try to talk to the device, defaulting to y, thus keeping the current behavior. If unset, the battery will always be registered without checking the sanity of the connection.
Signed-off-by: Frans Klaver <frans.klaver@xsens.com> --- If there's a better place to arrange for this all to happen, or to make this more common across power supplies, I'm perfectly happy to do that work instead. For now this seems like the logical step to take, especially since using device tree was (sensibly) shot down last september [0].
[0] https://lkml.org/lkml/2014/9/24/479
drivers/power/Kconfig | 8 ++++++++ drivers/power/sbs-battery.c | 8 ++++++-- 2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig index 87f8cb01fbee..9cb74ce26629 100644 --- a/drivers/power/Kconfig +++ b/drivers/power/Kconfig @@ -157,6 +157,14 @@ config BATTERY_SBS Say Y to include support for SBS battery driver for SBS-compliant gas gauges. +config BATTERY_SBS_TRY_PROBE + bool "Try communicating with SBS battery during probe" + depends on BATTERY_SBS + default y + help + Say Y to try to communicate with the SBS battery during probe. + Otherwise, always register the power supply. + config BATTERY_BQ27x00 tristate "BQ27x00 battery driver" depends on I2C || I2C=n diff --git a/drivers/power/sbs-battery.c b/drivers/power/sbs-battery.c index c7b7b4018df3..5582d5d49ab8 100644 --- a/drivers/power/sbs-battery.c +++ b/drivers/power/sbs-battery.c @@ -882,10 +882,14 @@ static int sbs_probe(struct i2c_client *client, skip_gpio: /* - * Before we register, we need to make sure we can actually talk + * Before we register, we might need to make sure we can actually talk * to the battery. */ - rc = sbs_read_word_data(client, sbs_data[REG_STATUS].addr); + if (IS_ENABLED(CONFIG_BATTERY_SBS_TRY_PROBE)) + rc = sbs_read_word_data(client, sbs_data[REG_STATUS].addr); + else + rc = 0; + if (rc < 0) { dev_err(&client->dev, "%s: Failed to get device status\n", __func__); -- 2.3.4
| |