drm/xe/rtp: Allow to OR rules

Some workarounds started to depend on different set of conditions where
the action should be applied if any of them match. See e.g.
commit 24d0d98af1c3 ("drm/xe/xe2lpm: Fixup Wa_14020756599"). Add
XE_RTP_MATCH_OR that allows to implement a logical OR for the rules.
Normal precedence applies:

	r1, r2, OR, r3

means

	(r1 AND r2) OR r3

The check is shortcut as soon as a set of conditions match.

v2: Do not match on empty number of rules-other-than-OR evaluated

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240618050044.324454-4-lucas.demarchi@intel.com

drivers/gpu/drm/xe/tests/xe_rtp_test.c

@@ -90,6 +90,59 @@ static const struct rtp_test_case cases[] = {
 			{}
 		},
 	},
+	{
+		.name = "match-or",
+		.expected_reg = REGULAR_REG1,
+		.expected_set_bits = REG_BIT(0) | REG_BIT(1) | REG_BIT(2),
+		.expected_clr_bits = REG_BIT(0) | REG_BIT(1) | REG_BIT(2),
+		.expected_count = 1,
+		.entries = (const struct xe_rtp_entry_sr[]) {
+			{ XE_RTP_NAME("first"),
+			  XE_RTP_RULES(FUNC(match_yes), OR, FUNC(match_no)),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(0)))
+			},
+			{ XE_RTP_NAME("middle"),
+			  XE_RTP_RULES(FUNC(match_no), FUNC(match_no), OR,
+				       FUNC(match_yes), OR,
+				       FUNC(match_no)),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(1)))
+			},
+			{ XE_RTP_NAME("last"),
+			  XE_RTP_RULES(FUNC(match_no), OR, FUNC(match_yes)),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(2)))
+			},
+			{ XE_RTP_NAME("no-match"),
+			  XE_RTP_RULES(FUNC(match_no), OR, FUNC(match_no)),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(3)))
+			},
+			{}
+		},
+	},
+	{
+		.name = "match-or-xfail",
+		.expected_reg = REGULAR_REG1,
+		.expected_count = 0,
+		.entries = (const struct xe_rtp_entry_sr[]) {
+			{ XE_RTP_NAME("leading-or"),
+			  XE_RTP_RULES(OR, FUNC(match_yes)),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(0)))
+			},
+			{ XE_RTP_NAME("trailing-or"),
+			  /*
+			   * First condition is match_no, otherwise the failure
+			   * wouldn't really trigger as RTP stops processing as
+			   * soon as it has a matching set of rules
+			   */
+			  XE_RTP_RULES(FUNC(match_no), OR),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(1)))
+			},
+			{ XE_RTP_NAME("no-or-or-yes"),
+			  XE_RTP_RULES(FUNC(match_no), OR, OR, FUNC(match_yes)),
+			  XE_RTP_ACTIONS(SET(REGULAR_REG1, REG_BIT(2)))
+			},
+			{}
+		},
+	},
 	{
 		.name = "no-match-no-add-multiple-rules",
 		.expected_reg = REGULAR_REG1,

drivers/gpu/drm/xe/xe_rtp.c

@@ -35,11 +35,18 @@ static bool rule_matches(const struct xe_device *xe,
 			 unsigned int n_rules)
 {
 	const struct xe_rtp_rule *r;
-	unsigned int i;
+	unsigned int i, rcount = 0;
 	bool match;
 
 	for (r = rules, i = 0; i < n_rules; r = &rules[++i]) {
 		switch (r->match_type) {
+		case XE_RTP_MATCH_OR:
+			/*
+			 * This is only reached if a complete set of
+			 * rules passed or none were evaluated. For both cases,
+			 * shortcut the other rules and return the proper value.
+			 */
+			goto done;
 		case XE_RTP_MATCH_PLATFORM:
 			match = xe->info.platform == r->platform;
 			break;
@@ -102,10 +109,27 @@ static bool rule_matches(const struct xe_device *xe,
 			match = false;
 		}
 
-		if (!match)
-			return false;
+		if (!match) {
+			/*
+			 * Advance rules until we find XE_RTP_MATCH_OR to check
+			 * if there's another set of conditions to check
+			 */
+			while (i < n_rules && rules[++i].match_type != XE_RTP_MATCH_OR)
+				;
+
+			if (i >= n_rules)
+				return false;
+
+			rcount = 0;
+		} else {
+			rcount++;
+		}
 	}
 
+done:
+	if (drm_WARN_ON(&xe->drm, !rcount))
+		return false;
+
 	return true;
 }
 

drivers/gpu/drm/xe/xe_rtp.h

@@ -179,6 +179,27 @@ struct xe_reg_sr;
 #define XE_RTP_RULE_IS_DISCRETE							\
 	{ .match_type = XE_RTP_MATCH_DISCRETE }
 
+/**
+ * XE_RTP_RULE_OR - Create an OR condition for rtp rules
+ *
+ * RTP rules are AND'ed when evaluated and all of them need to match.
+ * XE_RTP_RULE_OR allows to create set of rules where any of them matching is
+ * sufficient for the action to trigger. Example:
+ *
+ * .. code-block:: c
+ *
+ *	const struct xe_rtp_entry_sr entries[] = {
+ *		...
+ *		{ XE_RTP_NAME("test-entry"),
+ *		  XE_RTP_RULES(PLATFORM(DG2), OR, PLATFORM(TIGERLAKE)),
+ *		  ...
+ *		},
+ *		...
+ *	};
+ */
+#define XE_RTP_RULE_OR								\
+	{ .match_type = XE_RTP_MATCH_OR }
+
 /**
  * XE_RTP_ACTION_WR - Helper to write a value to the register, overriding all
  *                    the bits

drivers/gpu/drm/xe/xe_rtp_types.h

@@ -51,6 +51,7 @@ enum {
 	XE_RTP_MATCH_ENGINE_CLASS,
 	XE_RTP_MATCH_NOT_ENGINE_CLASS,
 	XE_RTP_MATCH_FUNC,
+	XE_RTP_MATCH_OR,
 };
 
 /** struct xe_rtp_rule - match rule for processing entry */