[PATCH libevdev] fix invalid absinfo range values reported by certain mtk soc

[Andreas Pokorny]

This change will only affect certain touch screens, for which the driver
integration code does not provide meaningful values for the allowed range
of ABS_MT_TRACKING_IDs. The reported range [0, 0] will be overwritten with
[-1, INT_MAX]

Signed-off-by: Andreas Pokorny <andreas.pokorny at canonical.com>
---
 libevdev/libevdev.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index 3a82fc7..2c87c3b 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -25,6 +25,7 @@
 #include <poll.h>
 #include <stdlib.h>
 #include <string.h>
+#include <limits.h>
 #include <unistd.h>
 #include <stdarg.h>
 #include <stdbool.h>
@@ -126,6 +127,24 @@ libevdev_dflt_log_func(enum libevdev_log_priority priority,
 	vfprintf(stderr, format, args);
 }
 
+static void
+fix_invalid_absinfo(const struct libevdev *dev,
+		  int axis,
+		  struct input_absinfo* abs_info)
+{
+	/*
+	 * The reported absinfo for ABS_MT_TRACKING_ID is sometimes
+	 * uninitialized for certain mtk-soc, due to init code mangling
+	 * in the vendor kernel.
+	 */
+	if (axis == ABS_MT_TRACKING_ID &&
+	    abs_info->maximum == abs_info->minimum) {
+		abs_info->minimum = -1;
+		abs_info->maximum = 0x7FFFFFFF;
+                log_bug(dev, "Invalid input_absinfo structure for ABS_MT_TRACKING_ID provided\n");
+	}
+}
+
 /*
  * Global logging settings.
  */
@@ -431,6 +450,8 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 			if (rc < 0)
 				goto out;
 
+			fix_invalid_absinfo(dev, i, &abs_info);
+
 			dev->abs_info[i] = abs_info;
 		}
 	}
-- 
2.1.4