On 02/02/21 10:04, Chenyi Qiang wrote:

 #define DR6_FIXED_1	0xfffe0ff0
-#define DR6_INIT	0xffff0ff0
+/*
+ * DR6_ACTIVE_LOW is actual the result of DR6_FIXED_1 | ACTIVE_LOW_BITS.
+ * We can regard all the current FIXED_1 bits as active_low bits even
+ * though in no case they will be turned into 0. But if they are defined
+ * in the future, it will require no code change.
+ * At the same time, it can be served as the init/reset value for DR6.
+ */
+#define DR6_ACTIVE_LOW	0xffff0ff0
 #define DR6_VOLATILE	0x0001e00f
 

Committed with some changes in the wording of the comment.

Also, DR6_FIXED_1 is (DR6_ACTIVE_LOW & ~DR6_VOLATILE).

Paolo