On Wed, Sep 24, 2014 at 02:11:17PM +0100, Frans Klaver wrote: > In some cases you want to instantiate a battery even before it is > attached; it is perfectly reasonable for a device to start up on > wall-power and be connected to a battery later. The current advice is to > instantiate a device explicitly in the kernel, or probe for the device > from userspace. The downside of these approaches is that the user needs > to keep the information related to the i2c battery in different places, > which is inconvenient.
This really sounds like a Linux policy issue rather than something that should be described in dt. Presumably there's a reason we sanity cehck this in the first place. What happens while the battery isn't plugged in? What can fail, and how? Mark. > Add the "sbs,always-present" option to the device tree. If set, the > battery is instantiated without sanity checking the connection. >From the description above, this name is incorrect. You're adding this property to work around the battery _not_ being present at probe-time. >From a binding point of view, "instantiated" is somewhat meaningless -- that's an OS level detail rather than a contract detail. Mark. > > Signed-off-by: Frans Klaver <[email protected]> > --- > drivers/power/sbs-battery.c | 11 +++++++++-- > include/linux/power/sbs-battery.h | 3 +++ > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/power/sbs-battery.c b/drivers/power/sbs-battery.c > index b5f2a76..5d327b5 100644 > --- a/drivers/power/sbs-battery.c > +++ b/drivers/power/sbs-battery.c > @@ -651,6 +651,9 @@ static struct sbs_platform_data *sbs_of_populate_pdata( > if (!rc) > pdata->poll_retry_count = prop; > > + pdata->always_present = of_property_read_bool(of_node, > + "sbs,always-present"); > + > if (!of_get_property(of_node, "sbs,battery-detect-gpios", NULL)) { > pdata->battery_detect = -1; > goto of_out; > @@ -761,10 +764,14 @@ 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 (!pdata->always_present) > + 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__); > diff --git a/include/linux/power/sbs-battery.h > b/include/linux/power/sbs-battery.h > index 2b0a9d9..724bd9b 100644 > --- a/include/linux/power/sbs-battery.h > +++ b/include/linux/power/sbs-battery.h > @@ -31,12 +31,15 @@ > * @i2c_retry_count: # of times to retry on i2c IO failure > * @poll_retry_count: # of times to retry looking for new > status after > * external change notification > + * @always_present: the device is instantiated even if the battery > + * is not physically present > */ > struct sbs_platform_data { > int battery_detect; > int battery_detect_present; > int i2c_retry_count; > int poll_retry_count; > + bool always_present; > }; > > #endif > -- > 2.1.0 > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
