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

commit 282e4637bc1c0b338708bcebd09d31c69abec070 upstream.

Commit 025bcc1 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: 025bcc1540 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 1cb79925730d931a0ee00f3ff0f470464731d3b3..623be90704abfb0ca987ae3aa4184bd97d4c1e3a 100644 (file)
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -164,19 +164,21 @@ static int wacom_pl_irq(struct wacom_wac *wacom)
                wacom->id[0] = STYLUS_DEVICE_ID;
        }
 
-       pressure = (signed char)((data[7] << 1) | ((data[4] >> 2) & 1));
-       if (features->pressure_max > 255)
-               pressure = (pressure << 1) | ((data[4] >> 6) & 1);
-       pressure += (features->pressure_max + 1) / 2;
-
-       input_report_abs(input, ABS_X, data[3] | (data[2] << 7) | ((data[1] & 0x03) << 14));
-       input_report_abs(input, ABS_Y, data[6] | (data[5] << 7) | ((data[4] & 0x03) << 14));
-       input_report_abs(input, ABS_PRESSURE, pressure);
-
-       input_report_key(input, BTN_TOUCH, data[4] & 0x08);
-       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) {
+               pressure = (signed char)((data[7] << 1) | ((data[4] >> 2) & 1));
+               if (features->pressure_max > 255)
+                       pressure = (pressure << 1) | ((data[4] >> 6) & 1);
+               pressure += (features->pressure_max + 1) / 2;
+
+               input_report_abs(input, ABS_X, data[3] | (data[2] << 7) | ((data[1] & 0x03) << 14));
+               input_report_abs(input, ABS_Y, data[6] | (data[5] << 7) | ((data[4] & 0x03) << 14));
+               input_report_abs(input, ABS_PRESSURE, pressure);
+
+               input_report_key(input, BTN_TOUCH, data[4] & 0x08);
+               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;