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SubjectRe: [PATCH 1/2] HID: input: map digitizer battery usage
On Tue, Aug 01, 2017 at 04:35:33PM +0200, Jiri Kosina wrote:
> On Mon, 31 Jul 2017, Dmitry Torokhov wrote:
>
> > We already mapped battery strength reports from the generic device
> > control page, but we did not update capacity from input reports, nor we
> > mapped the battery strength report from the digitizer page, so let's
> > implement this now.
> >
> > Batteries driven by the input reports will now start in "unknown" state,
> > and will get updated once we receive first report containing battery
> > strength from the device.
> >
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > ---
> > drivers/hid/hid-input.c | 181 ++++++++++++++++++++++++++++++++----------------
> > include/linux/hid.h | 2 +
> > 2 files changed, 124 insertions(+), 59 deletions(-)
> >
> > diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> > index ccdff1ee1f0c..5bcd4e4afb54 100644
> > --- a/drivers/hid/hid-input.c
> > +++ b/drivers/hid/hid-input.c
> > @@ -340,13 +340,42 @@ static unsigned find_battery_quirk(struct hid_device *hdev)
> > return quirks;
> > }
> >
> > +static int hidinput_scale_battery_capacity(struct hid_device *dev,
> > + int value)
> > +{
> > + if (dev->battery_min < dev->battery_max &&
> > + value >= dev->battery_min && value <= dev->battery_max)
> > + value = ((value - dev->battery_min) * 100) /
> > + (dev->battery_max - dev->battery_min);
> > +
> > + return value;
> > +}
> > +
> > +static int hidinput_query_battery_capacity(struct hid_device *dev)
> > +{
> > + u8 *buf;
> > + int ret;
> > +
> > + buf = kmalloc(2, GFP_KERNEL);
> > + if (!buf)
> > + return -ENOMEM;
> > +
> > + ret = hid_hw_raw_request(dev, dev->battery_report_id, buf, 2,
> > + dev->battery_report_type, HID_REQ_GET_REPORT);
> > + ret = (ret != 2) ? -ENODATA : buf[1];
> > +
> > + kfree(buf);
> > +
> > + return hidinput_scale_battery_capacity(dev, ret);
>
> Is it intentional that you call hidinput_scale_battery_capacity() here
> even in 'ret == -ENODATA' case?
>
> It wouldn't actually break anything currently, as the
>
> value >= dev->battery_min
>
> check in hidinput_scale_battery_capacity() would most likely ensure that
> the value wouldn't get overwritten and then propagated back, but it's
> confusing and error-prone wrt. any future changes.
> Or have I missed something?

No, you are totally right, I'll resent the series in a few.

Thanks.

--
Dmitry

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