Commit 282e4637 authored Jan 26, 2017 by Jason Gerecke Committed by Jiri Kosina Jan 26, 2017

HID: wacom: Fix poor prox handling in 'wacom_pl_irq'



Commit 025bcc15 performed cleanup work on the 'wacom_pl_irq' function, making
it follow the standards used in the rest of the codebase. The change
unintiontionally allowed the function to send input events from reports
that are not marked as being in prox. This can cause problems as the
report values for X, Y, etc. are not guaranteed to be correct. In
particular, occasionally the tablet will send a report with these values
set to zero. If such a report is received it can caus an unexpected jump
in the XY position.

This patch surrounds more of the processing code with a proximity check,
preventing these zeroed reports from overwriting the current state. To
be safe, only the tool type and ABS_MISC events should be reported when
the pen is marked as being out of prox.

Fixes: 025bcc15 ("HID: wacom: Simplify 'wacom_pl_irq'")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

parent a9ce7856

drivers/hid/wacom_wac.c

+15 −13

Original line number	Diff line number	Diff line
		@@ -166,6 +166,7 @@ static int wacom_pl_irq(struct wacom_wac *wacom)
		wacom->id[0] = STYLUS_DEVICE_ID;
		}

		if (prox) {
		pressure = (signed char)((data[7] << 1) \| ((data[4] >> 2) & 1));
		if (features->pressure_max > 255)
		pressure = (pressure << 1) \| ((data[4] >> 6) & 1);
		@@ -179,6 +180,7 @@ static int wacom_pl_irq(struct wacom_wac *wacom)
		input_report_key(input, BTN_STYLUS, data[4] & 0x10);
		/* Only allow the stylus2 button to be reported for the pen tool. */
		input_report_key(input, BTN_STYLUS2, (wacom->tool[0] == BTN_TOOL_PEN) && (data[4] & 0x20));
		}

		if (!prox)
		wacom->id[0] = 0;

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