[PATCH] Input: spaceball - fix parsing of movement data packets
flat view
STALE1756d
From: Leo L. Schwab <hidden>
Date: 2021-07-27 04:39:14
Also in:
lkml
Subsystem:
input (keyboard, mouse, joystick, touchscreen) drivers, the rest · Maintainers:
Dmitry Torokhov, Linus Torvalds
The spaceball.c module was not properly parsing the movement reports coming from the device. The code read axis data as signed 16-bit little-endian values starting at offset 2. In fact, axis data in Spaceball movement reports are signed 16-bit big-endian values starting at offset 3. This was determined first by visually inspecting the data packets, and later verified by consulting: http://spacemice.org/pdf/SpaceBall_2003-3003_Protocol.pdf If this ever worked properly, it was in the time before Git... Signed-off-by: Leo L. Schwab <redacted> --- drivers/input/joystick/spaceball.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/input/joystick/spaceball.c b/drivers/input/joystick/spaceball.c
index 429411c6c0a8..43bfb3d2fa8a 100644
--- a/drivers/input/joystick/spaceball.c
+++ b/drivers/input/joystick/spaceball.c@@ -74,10 +74,20 @@ static void spaceball_process_packet(struct spaceball* spaceball) switch (spaceball->data[0]) { case 'D': /* Ball data */ + /* + * Skip first three bytes; read six axes worth of data. + * Axis values are signed 16-bit big-endian. + */ if (spaceball->idx != 15) return; - for (i = 0; i < 6; i++) - input_report_abs(dev, spaceball_axes[i], - (__s16)((data[2 * i + 3] << 8) | data[2 * i + 2])); + data += 3; + for (i = 0; + i < ARRAY_SIZE(spaceball_axes); + ++i, data += sizeof(__s16)) { + input_report_abs( + dev, + spaceball_axes[i], + (__s16)((data[0] << 8) | data[1])); + } break; case 'K': /* Button data */
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2.32.0